I love this puzzle. What a great idea to use those qualifying words we see so frequently in crossword puzzle clues in the place of the old "e.g," but by removing the COMMA, make it seem like they're not qualifying. Talk about TRICKERY! The reveal is highlighted by the excellent clue at 74A: Punctuation mark missing in "Let's eat people!" (at least one would hope!).
Thus, 1A: *Leave briefly (VACAY) is really meant to be "leave, briefly," or a short way of saying "vacation." The others play on "say," "for one," and "frequently." 41A: *All for one (LAUNDRYDETERGENT) is simply brilliant. How completely the meaning changes with that added comma! I don't love the answer COURSEEXAM. I'm not sure what would have worked better, but it's really a small complaint.
Some other nice things in this better than typical Wednesday include things like the casual phrases TOBEFAIR and THATSODD. I also enjoyed the presence of TWEEDLEDUM. I had to leave the last two letters blank for a little bit to be certain I had the right one!
Tough clue at 16A: Mystical character (RUNE). I tried gUru at first, and then had to fill in everything with crosses once I'd taken out the wrong letters. I didn't expect that kind of character! Also a nice gendered misdirect with 30D: Some playground attendants (DADS). I recall those days with some fair degree of nostalgia.