Pay this last work force (5)
I believe the answer is:
screw
'pay' is the definition.
(I've seen this before)
'this last work force' is the wordplay.
'last' suggests the final letters.
'work force' becomes 'crew' (I've seen this in another clue).
The final letter of 'this' is 's'.
's'+'crew'='SCREW'
(Other definitions for screw that I've seen before include "Prison officer (slang)" , "Threaded fixer" , "Take advantage of" , "shot in pool hall" , "fast turn" .)