Gain for female with sex appeal (6)
I believe the answer is:
profit
'gain' is the definition.
(I know that gain can be written as profit)
'for female with sex appeal' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'female' becomes 'f' (common abbreviation).
'with' says to put letters next to each other.
'sex appeal' becomes 'it'.
'pro'+'f'+'it'='PROFIT'
(Other definitions for profit that I've seen before include "It's gained on a transaction" , "Yield - gain" , "returns" , "Surplus earnings" , "Financial gain" .)