Squash British enthusiast, contain voice (9)
I believe the answer is:
butternut
'squash' is the definition.
(butternut squash is a kind of squash)
'british enthusiast contain voice' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'enthusiast' becomes 'nut' (nut can mean an enthusiast or fan).
'contain' means one lot of letters goes inside another.
'voice' becomes 'utter' (I've seen this in another clue).
'b'+'nut'='bnut'
'bnut' placed around 'utter' is 'BUTTERNUT'.
(Other definitions for butternut that I've seen before include "sort of a squash" , "species of tree" , "Wood" , "Variety of pumpkin" .)