Test car — keep away, they say (8)
I believe the answer is:
audition
'test' is the definition.
(audition is a kind of test)
'car keep away they say' is the wordplay.
I cannot really understand how this works, but
'car' could be 'audi' (audi is a german car brand) and 'audi' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for audition that I've seen before include "Hearing for a part-seeking actor" , "ability to hear" , "(Actor's) test interview" , "Test for suitability as performer" , "Hearing for actor competing for part" .)