Such a road wrecked a trailer (8)
I believe the answer is:
arterial
'such a road' is the definition.
(arterial road is a kind of road)
'wrecked a trailer' is the wordplay.
'wrecked' indicates anagramming the letters.
'a'+'trailer'='atrailer'
'atrailer' with letters rearranged gives 'ARTERIAL'.
(Other definitions for arterial that I've seen before include "Like certain vessels" , "Of blood vessels (and other important routes)" , "Major route with minor branches" , "Like a main road" , "Road that connects towns or cities" .)