Car horn (6)
I believe the answer is:
hooter
'car horn' is the definition.
(I know that car horn can be written as hooter)
This is the entire clue.
(Other definitions for hooter that I've seen before include "Uphill stone pusher (Gk. myth)" , "it smells" , "Factory siren" , "Car horn or slang nose" , "owl?" .)