Player on stage removing agent’s head (5)
I believe the answer is:
actor
'player on stage' is the definition.
(someone performing on a stage)
I cannot understand how the rest of the clue works.
(Other definitions for actor that I've seen before include "Croat (anag.)" , "Cruise maybe" , "Cruise, e.g." , "Films/stage worker" , "Person performing on stage or screen" .)