Swimming every gala in a mediocre fashion (9)

I believe the answer is:

averagely

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'in a mediocre fashion' is the definition.
I can't tell whether this defines the answer.

'swimming every gala' is the wordplay.
'swimming' is an anagram indicator.
'every'+'gala'='everygala'
'everygala' is an anagram of 'AVERAGELY'.

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I've seen this clue in The Independent.

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