Female friend returned sailor's biscuit (8)
I believe the answer is:
flapjack
'biscuit' is the definition.
(I've seen this before)
'female friend returned sailor's' is the wordplay.
'female' becomes 'f' (abbreviation).
'friend' becomes 'pal' (pal is a kind of friend**).
'returned' says the letters should be written in reverse.
'sailor' becomes 'jack' (I've seen this before).
'pal' written backwards gives 'lap'.
'f'+'lap'+'jack'='FLAPJACK'
(Other definitions for flapjack that I've seen before include "Thick oat biscuit" , "Chewy cake with oats and syrup" , "American pancake" , "It's sweet" , "Oaty biscuit; US pancake" .)