Title: Chop to it
Author: David J. Kahn
Theme: is spelled out at 39a: Antelope with spiraled horns (and a hint to this puzzle's theme) (ADDAX). In other words, the letters A and X are added to common phrases to create new and unexpected answers that are then clued. Like most themes it's easier to show than to spell out:
18a: Levy on cover girls? (MODELTAX).

60a: Try to influence a game show leader? (COAXHOST).
3d: Person born in northwest Germany 1,500 years ago? (NATIVESAXON).
6d: Deception requiring a vote recount? (TALLYHOAX).

25d: Is a student in a housekeeping course? (TAKESWAXING). Also, I guess, a class one might take in cosmetology

36d: Dissertation about neuron appendages? (AXONPAPER). My least favorite of the themed entries -- because I'm not too hip on sub-atomic stuff and I can't find a picture of an axon.
Sunny Spots:
52a: Place for steamers? (SPA). Love those sauna jokes.
26d: NPR's Hansen (LIANE). Co-host with Will Shortz of the NPR Weekend Edition Sunday Puzzle, which I will win someday.
9d: Start of a noted palindrome (MADAM). As in "Madam, I'm Adam." My first thought was AMANA, as in the start to another noted palindrome "A man, a plan, a canal, Panama."
Suns of Bitches: Nothing really, although I did not and still don't know anything about "Knuffle Bunny" so 47d: Girl in the "Knuffle Bunny" books (TRIXIE) was tough.
Sundries: (Presented sans commentary due to poor time management)
1a: Like some yogurt (NONFAT).
7a: Chip maker (IBM).
10a: With 35-Across, die (PASS).
14a: "Spamalot" costar (AZARIA).
15a: Prix fixe alternative (ALACARTE).
17a: "I want to hear all the details" (DOTELL).
19a: "Idylls of the King" name (ENID).
20a: "Otello" premiere locale (LASCALA).
22a: Accelerate, with "up" (REV).
23a: Edgar Allan Poe character Arthur Gordon ___ (PYM).

24a: Courage and fortitude (METTLE).
28a: Spellbind (ENCHANT).32a: Adjust one's sights, maybe (REAIM).
33a: Language of Afghanistan (PASHTO).
35a: See 10-Across (AWAY).
37a: Jazz trombonist Winding (KAI).
38a: 60-year-old carrier (ELAL).
41a: Fender flaw (DENT).
42a: ___-en-Provence (AIX).
43a: 11% of DC (LXVI).
44a: Weights (ONUSES).
46a: Franklin (CNOTE).
48a: Sherbet variety (RAINBOW).
50a: Matisse and others (HENRIS).
53a: Galoot (APE).
56a: "Understood" (IGOTCHA).
59a: Line through the poles (AXIS).
63a: Cans (POKIES).
65a: What a zigzag line might represent in a schematic (RESISTOR).
66a: Make clear (EVINCE).
67a: False negative? (TRUE).
68a: Fashion monogram (YSL).
69a: Kitchen appliances (RANGES).
1d: LaDuke was his vice presidential running mate in 1996 and 2000 (NADER).
2d: Triatomic form of oxygen (OZONE).
4d: Ethel's husband (FRED).
5d: Be hurting (AIL).
7d: Cat food brand (IAMS).
8d: Cartel (BLOC).
10d: Epicurean sense (PALATE).
11d: Works at the Whitney (ART).
12d: D.C.'s Union, for one (STA).
13d: Census form info (SEX).
16d: Waldorf salad ingredient (CELERY).
21d: Org. with a staff of Aesculapius logo (AMA).
23d: Mtge. point, for example (PCT).
27d: Gives out (EMITS).
29d: Wild bunch?: Abbr. (NHL).
30d: First name at the 1976 Summer Olympics (NADIA).
31d: "You're going to like us" sloganeer (TWA).
33d: Crayola color that used to be called Flesh (PEACH).
34d: Dress with a flared skirt (ALINE).
40d: TiVo, e.g. (DVR).
41d: Couple (DUO).
43d: Vivien and Janet of filmdom (LEIGHS).
45d: It has four franchises in Calif. (NBA).49d: Freak ending? (ISH).
51d: Black, in a way (SOOTY).
54d: Knight, e.g. (PIECE).
55d: A lot of stress? (ESSES).
57d: General ___ chicken (TSOS).
58d: Keyboard key (CTRL).
59d: Having a similar quality (AKIN).
60d: Monitor, for short (CRT).
61d: "Jingle Bells" contraction (OER).
62d: Tempe inst. (ASU).
64d: Fertilizable gametes (OVA).
Today's puzzle was brought to you by your friendly neighborhood addax.
Have a nice Thursday, Norrin