Go off scratching head after bee sting (4)
I believe the answer is:
burn
'sting' is the definition.
('burn' can be a synonym of 'sting')
'go off scratching head after bee' is the wordplay.
'go off scratching head' becomes 'urn' (I can't explain this - if you can you should believe this answer much more).
'after' means one lot of letters go next to another.
'bee' becomes 'b'.
'urn' after 'b' is 'BURN'.
Can you help me to learn more?
(Other definitions for burn that I've seen before include "runner?" , "Go up in smoke" , "Catch light; stream" , "Incinerate" , "Severely overcook" .)