Cops can make a cop lie! (6)
I believe the answer is:
police
'cops' is the definition.
(cops can informally mean the police)
'make a cop lie' is the wordplay.
'make' is an anagram indicator.
'cop'+'lie'='coplie'
'coplie' anagrammed gives 'POLICE'.
'can' is the link.
(Other definitions for police that I've seen before include "9a 19d" , "Civil force" , "Keep watch on" , "... custodians of law and order" , "Nick" .)