What happens in autumn, but not at first, to earwig (9)
I believe the answer is:
eavesdrop
'earwig' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
(Other definitions for eavesdrop that I've seen before include "Listen secretly to others' conversations" , "Snoop" , "Overhear" , "spy" , "Listen to others' conversation" .)