Obstruction blocking road, could be a wheel (8)
I believe the answer is:
roulette
'a wheel' is the definition.
(roulette is a kind of wheel)
'obstruction blocking road' is the wordplay.
'obstruction' becomes 'let' (I've seen this in other clues).
'blocking' indicates putting letters inside.
'road' becomes 'route' (synonyms).
'let' placed within 'route' is 'ROULETTE'.
'could be' is the link.
(Other definitions for roulette that I've seen before include "gambling business" , "Game of chance with small ball" , "sort of gambling" , "Form of gambling" , "Wheel for the gambler" .)