Way round to allow casino game (8)
I believe the answer is:
roulette
'casino game' is the definition.
(I've seen this before)
'way round to allow' is the wordplay.
'way' becomes 'route' (route is a kind of way).
'round' indicates putting letters inside.
'to allow' becomes 'let' ('let' can be a synonym of 'allow').
'route' enclosing 'let' is 'ROULETTE'.
(Other definitions for roulette that I've seen before include "Gambling activity" , "risky venture" , "it's for the better, supposedly" , "Table game" , "If Russian, it's a very dangerous game" .)