Officer and men cap oil production (9)
I believe the answer is:
policeman
'officer' is the definition.
('policeman' can be a synonym of 'officer')
'men cap oil production' is the wordplay.
'production' is an anagram indicator.
'men'+'cap'+'oil'='mencapoil'
'mencapoil' anagrammed gives 'POLICEMAN'.
'and' is the link.
(Other definitions for policeman that I've seen before include "Constabulary member" , "Member of the force" , "He's responsible for the maintenance of public order" , "Constable" , "Menial cop (anag)" .)