Lottery for the painters' guild? (3,5)

I believe the answer is:

art union

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This clue could be a double definition.

'lottery' is the first definition.
Both the definition and answer are singular nouns.
Perhaps there's a link between them I don't understand?

'painters' guild?' is the second definition.
The definition suggests a singular noun which matches the answer.

'for the' is the link.

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

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