Contest in which reversing vehicle gains a point (4)
I believe the answer is:
race
'contest' is the definition.
(race is a kind of contest)
'reversing vehicle gains a point' is the wordplay.
'reversing' says the letters should be written backwards.
'vehicle' becomes 'car' (car is a kind of vehicle).
'gains' means one lot of letters go next to another.
'a point' becomes 'e' (compass point).
'car' backwards is 'rac'.
'rac'+'e'='RACE'
'in which' is the link.
(Other definitions for race that I've seen before include "The ... is not to the swift (Bible)" , "Contest; nation" , "Run, dash" , "put their skates on" , "Move fast" .)