Doing away with swimming in big shoal (10)

I believe the answer is:

abolishing

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'doing away with' is the definition.
Although both the answer and definition are present participle verbs, I don't understand how one could define the other.

'swimming in big shoal' is the wordplay.
'swimming' is an anagram indicator.
'in'+'big'+'shoal'='inbigshoal'
'inbigshoal' with letters rearranged gives 'ABOLISHING'.

Can you help me to learn more?

(Another definition for abolishing that I've seen is " Formally ending (a practice)".)

I've seen this clue in The Telegraph.

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