Back briefly with vehicle attending gambling game (8)
I believe the answer is:
baccarat
'gambling game' is the definition.
'baccarat' can be an answer for 'game' (baccarat is a kind of game). I also know that 'gambling' relates to this answer.
'back briefly with vehicle attending' is the wordplay.
'briefly' means to remove the last letter.
'with' says to put letters next to each other.
'vehicle' becomes 'car' (car is a kind of vehicle).
'attending' becomes 'at' (e.g. at school means attending school).
'back' with its final letter taken away is 'bac'.
'bac'+'car'+'at'='BACCARAT'
(Other definitions for baccarat that I've seen before include "Gambling card-game" , "Card game in which players bet against the banker" , "Casino card game" , "Casino card-game" , "game of cards" .)