Briefly go round and pinch a root vegetable (6)
I believe the answer is:
turnip
'a root vegetable' is the definition.
(turnip is a kind of root vegetable)
'briefly go round and pinch' is the wordplay.
'briefly' means to remove the last letter.
'go round' becomes 'turn'.
'and' means one lot of letters go next to another.
'pinch' becomes 'nip' ('nip' can be a synonym of 'pinch').
'turn' with its final letter taken off is 'tur'.
'tur'+'nip'='TURNIP'
(Other definitions for turnip that I've seen before include "what you eat?" , "veggie" , "Watch" , "Large-rooted vegetable related to the cabbage" , "food item" .)