Vehicle owner crashed, showing signs of stress (8)
I believe the answer is:
careworn
'showing signs of stress' is the definition.
(I've seen this before)
'vehicle owner crashed' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'crashed' indicates an anagram.
'owner' is an anagram of 'eworn'.
'car'+'eworn'='CAREWORN'
(Other definitions for careworn that I've seen before include "Tired, unhappy" , "Run down by anxiety" , "worn-out" , "Haggard, drawn" , "stressed" .)