Well, I've got 3 left -
12A - Small fish? That's no good (6) - one of the first set of 6, I hope.
18A - Note found in organ (5) - another one of the first set of 6.
8D - Stop surprisingly near outside rim of skating rink (8) - got the first three letters and have the wrong letter (from the last word I think) but I am stuck.
Can't find the cultivars for the first 2. I have an answer that parses for !8A but can't find it as a real word yet alone what it needs to be to fit.
Any hints gratefully received.