Withdraw some rare tractors (7)
I believe the answer is:
retract
'withdraw' is the definition.
(I've seen this in another clue)
'some rare tractors' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'RETRACT' is hidden within 'rare tractors'.
(Other definitions for retract that I've seen before include "Revoke" , "Take back (statement)" , "Withdraw, take back" , "Withdraw (offer, statement etc)" , "Pull back (statements or claws, perhaps)" .)