Racer shares coach (5,3)
I believe the answer is:
stock car
'racer' is the definition.
(stock car is a kind of racer)
'shares coach' is the wordplay.
'shares' becomes 'stock'.
'coach' becomes 'car' (I've seen this in other clues).
'stock'+'car'='STOCK-CAR'
(Other definitions for stock car that I've seen before include "Vehicle adapted for bumping races" , "Production-line vehicle modified for racing" , "production saloon" , "Production vehicle used in racing" , "customised vehicle" .)