Swirling mists at sea in transition (10)

I believe the answer is:

metastasis

'transition' is the definition.
(thesaurus)

'swirling mists at sea' is the wordplay.
'swirling' is an anagram indicator.
'mists'+'at'+'sea'='mistsatsea'
'mistsatsea' with letters rearranged gives 'METASTASIS'.

'in' is the link.

(Another definition for metastasis that I've seen is " Transformation".)

I've seen this clue in The Independent.

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