17A: Paul Bunyan's admission in therapy?: I HATE TO AX (ask)
27A: Formal attire for Dumbo?: ELEPHANT TUX (tusk)
43A: Plant fiber used by moonshiners?: WHISKEY FLAX (flask)
56A: Diver's tank capacity?: OXYGEN MAX (mask)
11D: Catchall source of revenue?: MULTI-TAX (task)
36D: Keep a Northeastern fort under surveillance?: VIDEO DIX (disk)
WHISKEY FLAX is not an ideal theme entry, as there is still a SK there waiting to be swapped. DIX in the last one refers to Fort DIX, named for Civil War Major General John Adams DIX.
What other sk/X can you think of? Minsk/MINX came to my mind.
Another Mount Everest for me. My "Yes, I can" hope has now resigned to "Well, I tried". Very hard. I did not understand the theme until the very end.
1A: Queen described by Mercutio: MAB. Here is Mercutio's speech. From Shakespeare's "Romeo and Juliet". I'm used to the "Fairy queen" clue.
4A: Cornrow: PLAIT. Bo Derek wore cornrows in movie "10".
9A: Like much "Laugh-In" humor: CAMPY. What exactly is CAMPY? Is "Friends" CAMPY?
14A: Put away: ATE
15A: Dreads wearer: RASTA. Bob Marley is probably the most famous RASTA. Love his "No Woman, No Cry".
16A: Fertilized item: OVULE. And GAMETE (49A: 16-Across cell). I had trouble obtaining both. Needed "egg" for hint.
19A: Tees off: RILES
20A: Fish in a tank: TETRA
21A: Italian omelet served open-faced: FRITTATA. I have yet to try zucchini FRITTATA. I expect it to be very soggy.
23A: Museum assortment: RELICS
25A: Balk at: RESIST
31A: Place to unwind: TUB
32A: "A Perfect Spy" author: LE CARRE. Here is the book cover. I've never heard of it. John LE CARRE also wrote "The Constant Gardener".
33A: __kiri: HARA. HARA is "belly", kiri is "cut". The Japanese samurai suicide.
34A: Selfless sort: GIVER. Donor too.
37A: Ex-Fed chairman Alan Greenspan's alma mater: NYU. A rare gimme for me. Greenspan is a disciple of Ayn Rand.
38A: Not so strict: LAXER
39A: Computer operating system: UNIX. Windows for our computer.
40A: Tabloid topic: SCANDAL. A-Rod is dating Kate Hudson now.
42A: It's illegal to drop it: LSD. I did not know the slang meaning of drop: to ingest an illicit drug orally; swallow, according to dictionary.
47A: River of the Carolinas: PEE DEE. Stumped again.
50A: The Great Barrier Reel borders it: CORAL SEA. See this map. My first Poison is a Christmas gift from Queensland.
54A: Expectant parent, e.g.: NAMER
58A: Part of "CSI": CRIME. SCENE is 5 letter too.
59A: Baseball commissioner Bud: SELIG. He used to own Milwaukee Brewers.
60A: Verb suffix?: OSE. Verbose. I did not fall into the IZE trap.
61A: Hockey lineup, e.g.: HEXAD. A group of six. I was stumped. Know nothing about hockey.
62A: Borneo swinger: ORANG. Borneo is the third largest island in the world, after Greenland and New Guinea.
63A: 1985 video game release, initially: NES (Nintendo Entertainment System). Japanese kanji for Nintendo is literally "Trust heavens".
1D: French teacher: MAITRE. I thought it's PROFESOR.
2D: Following closely: AT HEEL
3D: __ wig: '60s fad item: BEATLE. I wonder how much this original wig is worth now.
4D: Service provider? PREACHER. Great clue.
5D: Back muscle, for short: LAT. I simply forgot. See this diagram. Short for latissimus dorsi.
6D: Starting: AS OF
7D: __-Tass: news agency: ITAR. The Russian news agency. ITAR stands for Information Telegraph Agency of Russia.
8D: Sitcom set in a garage: TAXI. No idea.
9D: Organ layer: CORTEX. Latin for "bark of a tree". I thought CORTEX refers to the brain, you know, cerebral CORTEX.
10D: Some athletic footwear: AVIAS
12D: You can get it from a blast: PLEASURE. I was picturing a dynamite blast.
13D: Check-box word: YES. I like this clue.
18D: Apartment with two staircases, perhaps: TRIPLEX. So, duplex is "Apartment with one staircase"?
22D: Loyal: TRUE
24D: __ fly: run-scoring out: SAC. Sacrifice fly.
26D: Way up the slope: T-BAR
28D: Folk singer Griffith: NANCI. Stranger to me. Wikipedia says she is the original singer of "From a Distance". I like Bette Miller's version.
29D "__ I might ...": TRY AS
30D: Jack's place: TRUNK
33D: Not a whole person?: HALF MAN. "Two and a HALF MAN" helped me with this answer.
34D: [Uh-oh!]: GULP. The square brackets suggest non-verbal behavior/gesture.
35D: Like many Woody Allen characters: INSECURE. Thought of NEUROTIC.
38D: Bomb big-time: LAY AN EGG. Multipe words always give me trouble.
40D: Kid-lit poet Silverstein: SHEL. He also wrote the music and lyrics for "A Boy Named Sue".
41D: B.S., e.g.: DEG. And SCH (55D: 41-Down awarder)
44D: Best Actor winner for "Save the Tiger" (1973): LEMMON (Jack). No idea. Great clip. Al Pacino looks so young.
45D: Drill command: AT EASE
46D: Persian king who captured Athens: XERXES. Sigh. I actually watched and liked "300", in which Gerard Butler the Spartan King leads 300 Spartans fighting against XERXES, very kinky looking in the film.
48D: Miller creation: DRAMA. Arthur Miller. Anyone tried FLOUR?
52D: Phys. activity: EXER (exercise). Not a familiar abbreviation to me.
53D: "The Clan of the Cave Bear" heroine: AYLA. Boy, I can never remember this Jean Auel character.
57D: Beefeater, e.g.: GIN. No idea. I've never heard of Beefeater GIN. Dictionary defines beefeater as "yeoman of the English royal guard or a warder of the Tower of London". Hence the guard label I suppose.
Thank you for the blog/private answers and comments, everyone. I appreciate and value every contribution.