Scrapping virus alert? Beyond one’s authority (5,5)

I believe the answer is:

ultra vires

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'beyond one's authority' is the definition.
I can't tell whether this definition defines the answer.

'scrapping virus alert?' is the wordplay.
'scrapping' indicates an anagram.
'virus'+'alert'='virusalert'
'virusalert' with letters rearranged gives 'ULTRA VIRES'.

Can you help me to learn more?

(Other definitions for ultra vires that I've seen before include "Beyond one's legal authority (Latin)" , "Beyond one's legal powers" .)

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