Wooden salver useful to smokers (3-4)

I believe the answer is:

ash-tray

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'useful to smokers' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'wooden salver' is the wordplay.
'wooden' becomes 'ash' (made of ash).
'salver' becomes 'tray' (I've seen this in another clue).
'ash'+'tray'='ASH-TRAY'

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I've seen this clue in the Evening Standard.

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