Unrest having been ill or indisposed (9)

I believe the answer is:

rebellion

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'unrest' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'been ill or indisposed' is the wordplay.
'indisposed' indicates anagramming the letters.
'been'+'ill'+'or'='beenillor'
'beenillor' with letters rearranged gives 'REBELLION'.

'having' acts as a link.

Can you help me to learn more?

(Other definitions for rebellion that I've seen before include "Rising" , "Defiance" , "Revolting" , "Insurrection, revolt" , "insurgence" .)

I've seen this clue in The Sun.

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