Game permitted during regular journey (8)
I believe the answer is:
roulette
'game' is the definition.
(roulette is a kind of game)
'permitted during regular journey' is the wordplay.
'permitted' becomes 'let' (I've seen this before).
'during' means one lot of letters goes inside another.
'regular journey' becomes 'route' (I've seen this before).
'let' placed within 'route' is 'ROULETTE'.
(Other definitions for roulette that I've seen before include "Game of chance with small ball" , "SPORT/GAME" , "Form of gambling" , "it's for the better, supposedly" , "If Russian, it's a very dangerous game" .)