I'd like to add my congratulations to Jonathan Crowther. What a performance!
I've been doing the Azed for about 10 years but I can't recall many that were trickier than this. Fiendish sums it up very well!
The main difficulty is the four letter words - trying to work out if they're all correctly sorted.
I have a full grid as well as the missing clue. What I can't find yet is what goes with the second half of 15d. Also unsure of the final letter of 25a, and are there two same endings in the topmost down 4 letter words?
I made a list of them all and tried to coordinate but there's a limited number of time you feel like doing that!