Allowed to enter course for a game (8)
I believe the answer is:
roulette
'for a game' is the definition.
(roulette is a kind of game)
'allowed to enter course' is the wordplay.
'allowed to' becomes 'let' (to let something happen is to allow it).
'enter' is an insertion indicator.
'course' becomes 'route' (I've seen this before).
'let' placed into 'route' is 'ROULETTE'.
(Other definitions for roulette that I've seen before include "Table game" , "Gambling game with small ball and revolving disc (8)" , "Gambling game with spinning wheel and ball" , "Wheel for the gambler" , "French gambling" .)