One artery runs back through that road (5)
I believe the answer is:
aorta
'one artery' is the definition.
(aorta is a kind of artery)
'runs back through that road' is the wordplay.
'runs back' says the letters should be written in reverse (I've seen 'running back' mean this).
'through' indicates a hidden word.
'atroa' is hidden in the letters of 'that road'.
'atroa' backwards is 'AORTA'.
(Other definitions for aorta that I've seen before include "Bloody channel" , "it's drawing blood!" , "Main artery from heart" , "Blood carrier" , "Large artery of the heart" .)