Auto option (7)
I believe the answer is:
spoiler
'auto option' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for spoiler that I've seen before include "Aircraft flap for slowing" , "Aerofoil on a fast car" , "One who has wrecked" , "Flap putting brake on" , "giveaway" .)