Wool eater (4)
I believe the answer is:
moth
'wool eater' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for moth that I've seen before include "Night flying insect" , "Small insect that lays its eggs in cloth or fabric" , "Insect drawn to flame" , "Lepidopteran" , "Night-flier" .)