Small car you finally grab in retreat (8)
I believe the answer is:
runabout
'small car' is the definition.
(I've seen this before)
'you finally grab in retreat' is the wordplay.
I cannot quite see how this works, but
'you' could be 'u' (homophones) and 'u' is present in the answer.
'grab' could be 'nab' (I've seen this before) and 'nab' is located in the answer.
'retreat' could be 'rout' (I have seen 'Disorderly retreat' mean 'rout' so perhaps 'retreat' could also mean 'rout') and 'rout' 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 runabout that I've seen before include "small aircraft" , "Small car for short trips" , "Small car for local use" , "light aircraft of this type" , "nippy car" .)