Chopper whirling at a strike (9)

I believe the answer is:

karateist

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

'whirling at a strike' is the wordplay.
'whirling' indicates an anagram.
'at'+'a'+'strike'='atastrike'
'atastrike' is an anagram of 'KARATEIST'.

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