Laying out old writer doing without oxygen (9)

I believe the answer is:

expending

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'laying out' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?

'old writer doing without oxygen' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'writer' becomes 'pen' (something which writes).
'without' is a deletion indicator.
'oxygen' becomes 'O' (atomic symbol for oxygen).
'doing' with 'o' taken out is 'ding'.
'ex'+'pen'+'ding'='EXPENDING'

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

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