Roofing stone is rubbish (5)

I believe the answer is:

slate

I believe this is a double definition.

'roofing stone' is the first definition.
(I've seen this in another clue)

'is rubbish' is the second definition.
(I've seen this before)

(Other definitions for slate that I've seen before include "Criticise harshly" , "Roofing tile" , "Roofing plate" , "Blast" , "Roof tile or pub credit" .)

I've seen this clue in The Sun.

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