As a game it is, you allow, way-out (8)
I believe the answer is:
roulette
'as a game it is' is the definition.
I can't tell whether this definition defines the answer.
'allow way-out' is the wordplay.
'allow' becomes 'let' (synonyms).
'way' becomes 'route' (route is a kind of way).
'out' indicates putting letters inside.
'let' inserted within 'route' is 'ROULETTE'.
'you' acts as a link.
Can you help me to learn more?
(Other definitions for roulette that I've seen before include "French gambling" , "gambling business" , "risky venture" , "sort of gambling" , "Gambling game with small ball and revolving disc (8)" .)