Sort of wheel allowed in the road (8)
I believe the answer is:
roulette
'sort of wheel' is the definition.
(I know that roulette is a type of wheel)
'allowed in the road' is the wordplay.
'allowed' becomes 'let' (to let is to allow or permit).
'in the' means one lot of letters goes inside another.
'road' becomes 'route' (synonyms).
'let' put inside 'route' is 'ROULETTE'.
(Other definitions for roulette that I've seen before include "If Russian, it's a very dangerous game" , "it's a gamble" , "Wheel of fortune" , "Gambling device" , "Wheel for the gambler" .)