Wow, this was a tough one! The clues were uniformly tricky, and even when I had an idea what they were getting at, the crosses were also so difficult that it sometimes took a break and coming back to the puzzle to get my brain in the right tack.
I broke into the puzzle with VIOLASOLO, an answer that was probably a "huh?" for most people, but which for me was straightforward as both my brother and his wife are professional violists. I tried smoOch at 31A: Sloppy kiss (WETONE), but figured out that was wrong when I put STAGESETS in. 26A: Loaded things? (BASES) took a while to figure out, especially since I wanted "peres" or "meres" for 26D: Members of la famille (BEBES). I never heard of a BIBELOT, so that took forever. And I misread 35A: Modern composer's constructions (TONEROWS) as "instructions".
Anyway, I had the entire NE filled in pretty quickly, so I thought things would go smoothly. Unfortunately not. I had TEENPOP going down into the SE, but I had BOXSters (?) at 33D: Some sports figures (BOXSCORE). I love that clue, especially as it misleads you into thinking the answer will end with an S. Finally, I guessed BAEZ for 45D, which enabled BOUNCEHOUSE. I actually think of those as bounce castles, but the entry googles well.
49A: Stopgap for an energy shortage (POWERNAP) is outstanding. I did not see it coming at all. The SE has very nice words in it, including ORANGINA, and ASANA right next to NEPAL.
Still, even with TIBIAS, _ALVES, and SNEEZE, I couldn't get any traction in the SW. It took a long time to see LIBRARIAN (sorry, Frannie), and 29D: Kosher (ALLOWABLE) was a tough get also. But the prize goes to 27D: Dog washers? (FOOTBATHS). Couldn't see it for the longest time! It took the breakthrough of seeing HOLY/GRAIL to open that section and finally break the rest of the NW.
- 7D: Sliding door locales (MINIVANS) - very nice and not what I was thinking of at all.
- 8D: Sting, e.g. (BASSIST) - I'd tried British multiple times.
- 2D: Northern hemisphere? (IGLOO) - lovely.
- 1A: One waiting to go off (TIMEBOMB) - I knew there had to be a bomb in here, but the answer is so perfect for the definition.
- 25A: Majors, e.g. (BRASS) - very tricky!
The 3-letter answers in this puzzle are:
- ITS: common contraction, easily gettable from the clue, even though I don't know the song
- LAG: common word, clued well enough.
- ROM: dated word in just about every way. Who records on disks any more? Streaming, baby. That's where it's at.
- IVE: common contraction, also easily gettable from the clue.
- ARA: crosswordese, but really really really hard to get from the clue, which refers to a constellation, Norma, I've never heard of before.
- TRU: title of a Broadway play that I got from the crosses.
Not bad, and the rest of the puzzle is an outstanding challenge.