Long drink containing very soft fruit (9)
I believe the answer is:
pineapple
'fruit' is the definition.
(pineapple is a kind of fruit)
'long drink containing very soft' is the wordplay.
'long' becomes 'pine' ('pine' can be a synonym of 'long'**).
'drink' becomes 'ale' (ale is a kind of drink).
'containing' indicates putting letters inside.
'very soft' becomes 'pp'.
'ale' enclosing 'pp' is 'apple'.
'pine'+'apple'='PINEAPPLE'
(Other definitions for pineapple that I've seen before include "Fruit (tree and fruit!)" , "bomb" , "One may go off" , "that might go off?" , "Large juicy tropical fruit, or a grenade" .)