Deceives when damsel is drunk (8)
I believe the answer is:
misleads
'deceives' is the definition.
(I've seen this before)
'damsel is drunk' is the wordplay.
'drunk' is an anagram indicator.
'damsel'+'is'='damselis'
'damselis' anagrammed gives 'MISLEADS'.
'when' is the link.
(Other definitions for misleads that I've seen before include "Directs wrongly" , "Sends astray or gives false impression to" , "Deceives or sends in wrong direction" , "Gives false information to" , "Wrongly advises" .)