Theme: A Man of Action - Action phrases ending with synonyms of "huge".
17A: Striding self-confidently: WALKING TALL
60A: Enjoying an extravagant existence: LIVING LARGE
11D: Shooting for the stars: AIMING HIGH
29D: Carrying on conceitedly: TALKING BIG
I'm not sure what else to to call these four words. Three (TALL, LARGE and BIG) relate to size but HIGH is about position. Does that make sense? UPDATE: I see now I should have considered both words in the entries as the theme, so C.C. and I changed my theme title.
Argyle here, it is a scrablely puzzle, 3 X's but no q or z. Two Across theme entries and two Down entries are all 11 letter long and are all 'in the language'. Very tightly focused theme, as is always the case with Nancy's puzzles.
And plenty of 7/8/9 - letter non-theme answers to cohere the whole grid.
6A: Movie music: SCORE. And SONG (31D. iTunes download).
11A: Cigar residue: ASH.
14A: Like loud crowds: AROAR.
15A: "Family Matters" nerd Steve: URKEL. The "Did I do that?" kid.
16A: "I like __": '50s campaign slogan: IKE.
19A: Blender setting: MIX.
20A: Having sufficient skill: ABLE.
21A: No-brainer college course: EASY A.
22A: Lamp-to-plug link: WIRE. I wanted CORD.
23A: God of thunder: THOR. Germanic and Norse mythology.
25A: Short races: SPRINTS. NASCAR Sprint Cup races, however, are not SPRINTS. Go figure!
27A: It's a virtue, so they say: PATIENCE.
31A: iTunes download: SONG. Today's theme SONG.
32A: Midterms, e.g.: EXAMS.
33A: Emitted a delighted sigh: AAHED.
35A: Beaver or boater: HAT.
38A: Tick off: RILE.
39A: Paid to play: ANTED. You put some money in the pot to be dealt into a hand of poker. Small stakes games might have a nickel ante and a quarter limit to any raises.
40A: Hepcat's jargon: JIVE.
41A: Condescending cluck: TSK.
42A: Climbing tool for frozen surfaces: ICE AX.
43A: TV host Philbin: REGIS. I liked it when his wife, Joy, would co-host.
44A: About, in a memo: IN RE.
46A: Words while delivering a blow: TAKE THAT. AND THAT, for a second blow.
48A: Team supporters, collectively: FAN BASE.
51A: Hobbling gait: GIMP.
52A: Tiny pond plant: ALGA.
53A: Aired, as a TV show: WAS ON.
55A: Wolf's shelter: LAIR. Check out the alternate meanings to LAIR.
59A: Dry gently, as tears: DAB.
62A: Brit. record co.: EMI. (Electric & Musical Industries Ltd.)
63A: "Maria __": 1940s song: ELENA. Beautiful.
64A: Kitchen tearjerker: ONION.
65A: Pooch: DOG.
66A: '50s Ford flop: EDSEL. A success in crosswords, though.
67A: Part of a Santa costume: BEARD.
Down
1D: Muted trumpet sound: WA-WA. How about a clip, Jazzbumpa?
2D: Mideast native: ARAB.
3D: Dice throw: ROLL.
4D: Provide a schedule slot (for): MAKE TIME.
5D: Indian title: SRI.
6D: Crop yielding a common sweetener: SUGARCANE.
7D: PC monitors: CRTS. What with flat screens now this might soon be 'former computer terminals or monitors that included a Cathode Ray Tube.'
8D: Gives the nod to: OKAYS.
9D: Went off the wagon, e.g.: RELAPSED.
10D: Right-angled pipe: ELL.
12D: Mini, midi or maxi: SKIRT.
13D: Whammies: HEXES.
18D: Casino sign gas: NEON. The Strip.
24D: "For __ a jolly ...": HE'S.
26D: Towel holder: ROD.
27D: Saucy: PERT.
28D: Graph's x or y: AXIS.
30D: Bother big-time: EAT AT.
34D: Six-sided: HEXAGONAL.
36D: Nike competitor: AVIA.
37D: Try out: TEST.
39D: Game in which "bullets" can be whatever card you decide: ACES WILD. "Bullets" is poker lingo for aces.
40D: 747, for one: JET PLANE.
42D: Nest egg component, for short: IRA.
43D: Sleep lab acronym: REM. That is an acronym not for the sleep lab itself but what they use for a stage of sleep, Rapid Eye Movement, characterized by dreaming.
45D: Org. with dribblers: NBA. National Basketball Association.
47D: Crowned checker: KING.
48D: Washed-out: FADED.
49D: San Antonio mission: ALAMO.
50D: Gutter sites: EAVES.
54D: Trig function: SINE.
57D: Operatic prince: IGOR. Prince IGOR is an opera in Russian by Alekander Borodin.
58D: Tear apart: REND. Past tense can be a tricky RENT.
61D: Soft toss: LOB.
Answer grid.
Argyle