It's a decent enough, cute little theme, isn't it? But it's starts on a slightly edgy note with KEEPITDOWN (17A: "That's enough!," to a hot dog-eating contestant?). Didn't a recent winner get disqualified for disgorging within seconds of the buzzer? No? Well… I'm not looking it up for you. You can do that on your own. (And keep in mind that I don't think videos are allowed in the comments.) And I briefly could thing only of collagen when reading CUTITOUT (51A: "That's enough!," to a collagist?), but surely Mr. Livengood means collage, in which various things are cut out and re-assembled. Much better.
I like the silly APESUIT (2D: Jungle film attire) and WHATNOT (25D: Miscellaneous things), and CREWTEAM (3D: Unit involved in a shell game?) had me fooled for quite a while. And speaking of that, there's a strong sports theme running throughout this puzzle: MATE, YARDS, SETS, EXACTA, and ORR.
There was plenty of good fill, really, and I like the unusual and fun clues for MIX (40A: Action verb that's also a Roman numeral) and CHA (25A: "____ -ching!" (cash register sound)). Overall, it's a very good Tuesday puzzle. The week is off to a great start!