Wet, woolly-headed little devil (4)
I believe the answer is:
wimp
'wet' is the definition.
(I've seen this before)
'woolly-headed little devil' is the wordplay.
'woolly-headed' becomes 'w' (this might be a standard abbreviation I've not previously seen).
'little devil' becomes 'imp' (an imp is a little demon).
'w'+'imp'='WIMP'
Can you help me to learn more?
(Other definitions for wimp that I've seen before include "Feeble individual" , "Weak-willed person" , "Ineffective type" , "doormat?" , "Informally, an ineffectual man" .)