Something telling son to nick a costly car (9)
I believe the answer is:
narrative
'something telling' is the definition.
I can't tell whether this defines the answer.
'son to nick a costly car' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
'car' could be 'rr' (Rolls Royce) and 'rr' is found within the answer.
'son' could be 'native' (I've seen this before) and 'native' is found within the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for narrative that I've seen before include "Account of connected events, a story" , "Telling a story" , "Popeye's vegetable" , "Story recounting events" , "Account describing events" .)