Tousled beauty had fun going topless (11)
I believe the answer is:
dishevelled
'tousled' is the definition.
(I've seen this before)
'beauty had fun going topless' is the wordplay.
'beauty' becomes 'dish' (slang term for an attractive person).
'had fun' becomes 'revelled'.
'going topless' means to remove the first letter.
'revelled' with its first letter taken off is 'evelled'.
'dish'+'evelled'='DISHEVELLED'
(Other definitions for dishevelled that I've seen before include "Untidy (in appearance)" , "(Of hair, clothes) untidy" , "Blowzy" , "Rumpled" , "Tousled" .)