Very tricky! Only nitpick is that as 4-A's answer is colloquial, maybe the clue for it should reflect this. Thanks for the puzzle - it challenged me in a way I enjoyed!
That was a lot of fun! And while I agree with An Ephemeral Collation that "acid" is fairly colloquial, nonetheless it's part of the scientific name of the drug: Lysergic acid diethylamide. But now that I sit here thinking about it, I can really see both sides of this, so I'm not saying either is right or wrong, just throwing out an idea.
