I don't like to look a gift horse in the mouth, but I'd say today's solver didn't need a lot of horse sense to complete this grid. Working the theme from the puzzle title to the fancy image made with the circled letters, they weren't horsing around. Oh, wait, yes they were. We raced through it, but this horse wasn't without a few Trojans. We hit two snags.15D, Hybrid musical instrument with a shoulder strap (KEYTAR) where it crossed with 38D Biblical dry measure (OMER), held us up for a while, but at least we knew that spot was trouble. When we considered the letter R for that spot, and said Keytar out loud, it finally made good horse sense. Neither of us was familiar with Omer, but I'm guessing that Huygens, with his extensive knowledge of the Bible, will have made hay with this one. Our other problem came from Frannie blithely putting in Sock instead of Deck (52 D, Really wallop) due to a soft spot for the word sock, meaning to strike, from the Philadelphia Story. Since I didn't know 52A, Star in the Swan constellation, SENEB seemed fine, although, here again, I'm sure Huygens was way out in front on this one. Luckily, and correctly, Horace was not happy with MoETS for 59A, Crosses, which led, finally, to the necessary corrections in that area.
Favorites: JANITOR (6D: Key employee?) ; SHIRLEY (24A: Temple in Hollywood) ; DIPLOMA (84D: Academic paper?) ; WAG, always a favorite (106D: Jokester) ; Kickin' it old school with TILTON (77A: Charlene who played Lucy on 'Dallas') ; and not one, but two clues that mention dumbwaiters (1D and 53D). Crazy.
Longshots: NBAERS (107A: Bull or Celtic) Ugh ; EYER (35A: Assessor) ; and HIKEUP (37A: Lift).
Over all, easy, but good, clean fun. There you have it, straight from the horse's mouth.