Monkey scratching back sees rook (4)
I believe the answer is:
scam
'rook' is the definition.
(I know that rook can be written as scam)
'monkey scratching back' is the wordplay.
'monkey' becomes 'scamp' (both can mean a mischievous child).
'scratching back' means to remove the last letter (scratch can mean to erase).
'scamp' with its last letter taken away is 'SCAM'.
'sees' is the link.
(Other definitions for scam that I've seen before include "Con trick" , "'A con, deception (4)'" , "Fraudulent trick or swindle" , "Fraud, dishonest scheme" , "Rip-off" .)