Fruit wine's cool (7)
I believe the answer is:
rosehip
'fruit' is the definition.
(fruit of a rose plant)
'wine's cool' is the wordplay.
'wine' becomes 'rose' (rose is a kind of wine).
'cool' becomes 'hip' (hip can mean cool or fashionable).
'rose'+'hip'='ROSEHIP'
(Other definitions for rosehip that I've seen before include "Fruit of a popular flower" , "Fruit of the brier" , "Fruit from flower providing syrup" , "Fruit of flower used for syrup" , "Berry for syrup" .)