Hearing politician backing car-maker (8)
I believe the answer is:
auditory
'hearing' is the definition.
(I've seen this before)
'politician backing car-maker' is the wordplay.
'politician' becomes 'tory' (term for a Conservative Party politician).
'backing' says to put letters next to each other.
'car-maker' becomes 'audi' (car manufacturer).
'tory' after 'audi' is 'AUDITORY'.
(Other definitions for auditory that I've seen before include "Via the ears" , "Related to the sense of hearing" , "as one hears" , "Relating to hearing" .)