In the following crossword, the clues are linked to each other as well as to the words on the grid. Where an explicit relationship is not mentioned, external references generally point to a previous clue, answer or theme. Similarities may exist in word structures, sounds, meanings... but I'll let you discover the connections.
/A stands for Across, /D for Down.
1-d/A: Two figures in English literature. One is a poet, the other a
novelist.
5-p/A: One of the novelist's characters.
3-s/D: Speaking of English, our three commonest letters.
12-p/A: This logically follows an "e."
13-s/D: All planar directions except "d."
7-l/A: Popular NBC-TV weekend letters (not "Letterman").
8-t/D: Asner + Sullivan.
10-h/D: Famous sitcom personality.
12-a/D: His residence.
8-a/A: Marcellinus, here quoted by Montaigne: "They [the Parthians] had
strong sturdy horses, covered with stout leather..."
1-q/D: Bring back under control (whoa).
14-l/A: Central Asian beasts of burden speak out about themselves.
8-s/D: Abbreviation for verb parading as a noun, or rodent.
13-k/A: Less than man or mouse, sometimes studies a book.
11-l/A: What fries them when they take a side walk.
3-t/D: French possessive pronoun has palindromic form.
6-p/A: So does this explosive compound.
6-a/A: Strike this goddess near it and you'll be sorry!
12-a/A: Related sounds...
8-e/D: Vowel parade in comic character exclamation...
1-i/D: Type of disturbance that it propagates.
1-l/D: Akin, these friends appear on cereal boxes.
3-b/D. What one raises to produce cereal topping.
2-r/D: A longer, skinnier variety.
1-l/A: Similar to 1-l/D, this may be hemi-, demi- and semi-attached.
1-o/D: One producer of such things in succession.
3-a/A: Choose either Alessandro or Domenico—their lot isn't vile.
11-g/A: Like an octave, a strong affirmation in Spanish.
14-o/D: Similarly, nothing.
8-f/D: Short for Fabray, or type of bread.
13-g/D: Homonymically, octogenarian munched.
13-g/A: Child one-tenth his age also was fed.
8-r/D: Reckless ambition.
16-l/A: Motivation for this desire.
12-q/D: What those without ambition may be accused of having.
7-g/A: What you may need at this point.
12-p/D: Doctor's suggestion: take two of these.
8-a/D: Book of anecdotes.
5-a/A: Re:
12-b/D: Place it between two chocolate rounds.
12-h/A: Is Bob Newhart's wife a local restauranteur?
11-i/D: What the lawyer did after falling in Pierre.
12-e/D: Lawyers can be rude, vicious and—
2-c/D: What a vicious animal (or lawyer) does to his teeth.
8-b/D: Still feeling bad, Pierre?
2-c/A: At the mall, ask the girl for a Sprite or chocolate cake.
2-l/A: Mortal-seeking nymphs.
1-e/D: "She was Dolly at school. She was Dolores on the dotted line. But in
my arms she was always..."
8-o/D: Later lady by same author.
3-a/D: Although exiled, he was this by birth.
17-l/A: These are good in the cake of 2-c/A.
11-l/D: On the subject of sweets, sounds like a non-pareil.
5-k/A: That's where you may find this still-abominable man.
11-j/D: When you talk diz way, what you seez wid.
5-k/D: Russian for the first person singular.
8-q/D: Short for explode, or a private eye.
1-f/D: Partial job description for a cannoneer.
1-p/D: How civilians may attend artillery practice.
13-t/D: Projectile: what whooshes up will come back down.
5-g/A: A lot of fighting went on here in the 70s.
1-h/D: SE Asian characteristics become what a chemist does to change
colors.
10-a/A: Unlucky element...
4-l/A: That is found in this mineral.
3-l/A: Visitors from space are mostly silicious.
15-l/A: Upstairs dining room in 8-a/A's time.
9-a/A: Point located somewhere beyond infinity,
at least when we're bored (no ad).
1-m/D: Left over: maybe a result of applying 2-l/A as a verb?
9-o/A: Restricted consumption.
8-c/D: Result: you might fit in one half of your dress.
13-a/A: Beauty baroness whose shop Whoopi visited.
15-a/A: In antonymous contrast, what hair washers are.
14-f/D: Whose man saved Whoopi and Jack in hair-raising gunplay.
14-a/A: Played out again.
12-c/D: American playwright awoke and sang.
6-j/D: Initials of what rises with wakefulness or anger.
1-g/D: Counter point where anger is vanquished.
13-p/A: Peaceful nights or songs.
16-c/A: Paused in the Psalms.
12-k/D: Precedes "shucks."
1-d/D: As I wander (deceptively?) I'm like a knight.
4-a/A: Field wanderers with a goal, they ain't Saints, but they live with
angels.
8-n/A: What they gain in a game.
11-m/D: What Steve may have to do to drop the sail from the yard.
8-p/D: Sweetbreads.
7-g/D: Looks like something served with pita, but leave it in your
garden.
12-d/D: Cultivator of garden peas, he predicted procreative patterns.
8-d/D: Suffix on his name marks the theory.
6-h/A: Mating of patterned cloth and satin.
10-n/D: A device to keep tabs on memory lane.
17-d/A: You recovered until the doctor laced your tonic with LSD.
12-r/D: What the old doc followed touchy with.
10-n/A: In his "Anthology," Margaret would have been been as great as
George, "but for an untoward fate."
1-n/D: Like the previous geniuses, how you should have completed this
puzzle.