Crossword Genius

Swimmer in freezing lake swallows a lot of water (6,4)

Ross

I believe the answer is:

arctic seal

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'swimmer in' is the definition.
The definition suggests an adjective which matches the answer.

'freezing lake swallows a lot of water' is the wordplay.
'freezing' becomes 'arctic' (synonyms).
'lake' becomes 'L' (geographical abbreviation).
'swallows' is an insertion indicator.
'a lot of water' becomes 'sea' (a large amount of water).
'arctic'+'l'='arcticl'
'arcticl' placed around 'sea' is 'ARCTIC SEAL'.

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I've seen this clue in The Independent.
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