Player left to go in second (5)
I believe the answer is:
black
'player' is the definition.
(I know that Black is a Actor)
'left to go in second' is the wordplay.
'left' becomes 'l' (common abbreviation).
'to go in' indicates putting letters inside.
'second' becomes 'back' (to second a motion is to back it).
'l' placed within 'back' is 'BLACK'.
(Other definitions for black that I've seen before include "Sort of guard, panther, jack or pudding..." , "(Of coffee) without milk" , "Without light" , "Served without milk" , "Colour of jet" .)