Good loser in game (5)
I believe the answer is:
sport
I believe this clue is a double definition.
'good loser' is the first definition.
(I've seen this in another clue)
'game' is the second definition.
(I've seen this before)
'in' is the link.
(Other definitions for sport that I've seen before include "Wear - game - generous type" , "Physical exertion and competition" , "Eg, cricket" , "Put on" , "Abnormal" .)