Officer in sauna chewed fruit (7)
I believe the answer is:
sultana
'fruit' is the definition.
(sultana is a kind of fruit)
'officer in sauna chewed' is the wordplay.
'officer' becomes 'lt' (abbreviation for lieutenant).
'in' means one lot of letters goes inside another.
'chewed' is an anagram indicator.
'sauna' is an anagram of 'suana'.
'lt' placed into 'suana' is 'SULTANA'.
(Other definitions for sultana that I've seen before include "Royal lady" , "Pale seedless raisin" , "Aunt Sal (anag)" , "sovereign's woman" , "sweet little thing" .)