Wheels off in plant (7)
I believe the answer is:
caraway
'plant' is the definition.
(caraway is a kind of plant)
'wheels off' is the wordplay.
'wheels' becomes 'car' (car wheel is a kind of wheel).
'off' becomes 'away' ('away' can be a synonym of 'off').
'car'+'away'='CARAWAY'
'in' is the link.
(Other definitions for caraway that I've seen before include "____ seeds, for cooking" , "Aromatic plant" , "Seed used as flavouring" , "Seeds used for flavouring" , "Umbelliferous plant" .)