Ahoy, Muggles!
The "someone who wears green" is a
"Boston Celtic" - a local favorite in these parts.

To solve, you first needed to find the 6 symmetrically-placed entries that could be "green." (i.e. 14A BERET, 16A ONION, 40A SCREEN, 42A TURTLE, 64A OLIVE, and 69A NOISE (similar to "white noise" but with nature sounds). Then using the hints at 58A
"Over/___: sports wager (and a hint to solving the meta)" (UNDER) and 27A
Has on, as a uniform (WEARS) you needed to find the 6 symmetrically-placed entries with basketball-related clues located directly "under" the green entries (i.e. 17A COURT, 19A ECLAT*, 44A LAYUPS, 45A TIPOFF, 73A ITSON, and 75A CAGER). The first letters of the "green" entries spelled B-O-S-T-O-N, and the first letters of the basketball entries spelled C-E-L-T-I-C.
*Okay, so to spell CELTIC I had to get a little "creative" with 19A ECLAT, which isn't really a basketball term per se. I was just using a little wordplay there with "Fanfare" as in viewing "Fare" for sports "Fans".
Finally, to accommodate the stacking of the theme entries, I had to use a 15X16 grid; however, given the meta answer, I felt it was appropriate that this grid was "taller" than average.
Thanks for solving, everyone!
@DavyGravy is up next on
"Smooth Sailing Sundays!"
Until next time!
Cap'n Rick