Second squad's salary (5)
I believe the answer is:
screw
'salary' is the definition.
(I've seen this before)
'second squad's' is the wordplay.
'second' becomes 's' (common abbreviation).
'squad' becomes 'crew' (crew is a kind of squad).
's'+'crew'='SCREW'
(Other definitions for screw that I've seen before include "Threaded pin" , "Prison officer (sl.)" , "fast turn" , "Prison officer (slang)" , "Stitch up" .)