Dog bites first to check (4)
I believe the answer is:
curb
'to check' is the definition.
(both can mean to limit or control)
'dog bites first' is the wordplay.
'dog' becomes 'cur' (both can mean a despicable person).
'bites first' becomes 'b' (1st letter of 'bites').
'cur'+'b'='CURB'
(Other definitions for curb that I've seen before include "[LIMITATION]" , "Bridle" , "Hold back or try to prevent" , "Control, limit" , "Restrain, inhibit" .)