Second team's inside men in charge (6)
I believe the answer is:
screws
'inside men in charge' is the definition.
(slang for prison wardens - 'inside' is in prison)
'second team's' is the wordplay.
'second' becomes 's' (common abbreviation).
'team's' becomes 'crew's' (crew is a kind of team).
's'+'crews'='SCREWS'
(Other definitions for screws that I've seen before include "Prisoner guards, colloquially" , "... men guarding prisoners" , "Fastner with spiral thread" , "Fasteners with threaded shanks" , "Fix in place (6)" .)