Spare cup’s outside, needs a wash (7)

I believe the answer is:

cleanup

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

'spare cup's outside' is the wordplay.
'spare' becomes 'lean' (similar in meaning).
'outside' indicates putting letters inside.
'lean' inserted into 'cup' is 'CLEANUP'.

'needs' is the link.

Can you help me to learn more?

I've seen this clue in The Hindu.

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