Sorry it took me so long to solve this; wonderful puzzle! Had to look up the parse of 7A just now (wonderful use of Heard, as @polyagonist pointed out), but that's not a bad thing.
I really enjoyed the surfaces for 8A, 18A, 10D, 14D, and 16D. I appreciate 9D, but I can definitely feel it doing work. 17A is the only clue I might quibble over: either [not] for a deletion or [leading assault] for A I'd be OK with, but both seems somewhat inexact.