Tarry substance (7)

I believe the answer is:

bitumen

(Other definitions for bitumen that I've seen before include "Material for road surfacing, roofing, etc" , "Substance for surfacing roads" , "Road's topping" , "Tarry substance used to surface roads and roofs" , "Asphalt" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.