Work with potential smoker making ledge above fireplace (12)

I believe the answer is:

chimneypiece

'ledge above fireplace' is the definition.
(another term for mantelpiece)

'work with potential smoker' is the wordplay.
'work' becomes 'piece' (eg a work of art is a piece).
'with' means one lot of letters go next to another.
'potential smoker' becomes 'chimney' (as in the phrase 'to smoke like a chimney').
'piece' after 'chimney' is 'CHIMNEYPIECE'.

'making' is the link.

I've seen this clue in The Times.

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