Some tyre tracks traced back in main road (6)
I believe the answer is:
artery
'main road' is the definition.
(I've seen this in another clue)
'some tyre tracks traced back' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'back' is a reversal indicator.
'yretra' is hidden within 'tyre tracks traced'.
'yretra' in reverse letter order is 'ARTERY'.
'in' is the link.
(Other definitions for artery that I've seen before include "Major blood vessel or road" , "Important transport route" , "main course" , "Blood vessel; important route" , "Blood vessel such as the aorta" .)