Metal fastener; salary (5)
I believe the answer is:
screw
This clue is a double definition.
'metal fastener' is the first definition.
(I've seen this in another clue)
'salary' is the second definition.
(I've seen this before)
(Other definitions for screw that I've seen before include "Fastener, rivet" , "Archimedes' invention" , "Fasten; propeller" , "something with thread" , "Wage - prison officer" .)