A single female? Wrong! (5)
I believe the answer is:
amiss
'wrong' is the definition.
(I know that wrong can be written as amiss)
'a single female?' is the wordplay.
'single female?' becomes 'miss'.
'a'+'miss'='AMISS'
(Other definitions for amiss that I've seen before include "(Gone) wrong" , "Faulty" , "inappropriately" , "Wrong (a girl!)" , "Taking wrong turn" .)