Fruit cooked? It used to be fired (9)
I believe the answer is:
grapeshot
'it used to be fired' is the definition.
(historical type of ammunition)
'fruit cooked?' is the wordplay.
'fruit' becomes 'grapes' (grapes are fruit).
'cooked?' becomes 'hot' (hot from cooking).
'grapes'+'hot'='GRAPESHOT'
(Other definitions for grapeshot that I've seen before include "Great Balls of Fire" , "slugs?" , "Describing ammunition" , "Small projectiles fired from cannon" , "Small iron balls fired from a cannon" .)