Tax producer of emissions (7)
I believe the answer is:
exhaust
I believe this clue is a double definition.
'tax' is the first definition.
(wear out)
'producer of emissions' is the second definition.
(part of a car)
(Other definitions for exhaust that I've seen before include "Wear, tire out" , "Sap - piped emission" , "Tire utterly or fumes-dispersing device in car" , "part of car - > tire?" , "Use up completely" .)