Easily-split rock, used for roofing (5)

I believe the answer is:

slate

(Other definitions for slate that I've seen before include "rock used in building" , "Run down" , "Stone used for roofing" , "Small blackboard - for deferred payments" , "Rubbish" .)

I've seen this clue in the Sydney Morning Herald.

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.