Started with roof coating (3)

I believe the answer is:

tar

'roof coating' is the definition.
(I've seen this in another clue)

'started with' is the wordplay.
'with' indicates a hidden word.
'TAR' is hidden within 'started'.

(Other definitions for tar that I've seen before include "Dark flammable liquid" , "Sticky road material or informal sailor" , "Hearty" , "Informal sailor, the rat" , "A sailor; a preservative" .)

I've seen this clue in The Mirror.

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