Car-part produced by a lousy drilling firm (4,5)
I believe the answer is:
tail light
If this is the answer I cannot explain how the clue works.
Can you help me to learn more?
(Other definitions for tail light that I've seen before include "fitting on back of bike?" , "car shows it braking" , "followers'll see it" , "Feature of Rover, say" , "motoring requisite" .)