Stir sodas up, making small bubble (4,3)

I believe the answer is:

soap sud

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'small bubble' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'stir sodas up' is the wordplay.
'stir' is an anagram indicator.
'sodas'+'up'='sodasup'
'sodasup' is an anagram of 'SOAP SUD'.

'making' is the link.

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

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