Whole eternity blown to bits (8)

I believe the answer is:

entirety

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'whole' is the definition.
(I know that whole can be written as entirety)

'eternity blown to bits' is the wordplay.
'eternity' anagrams to 'ENTIRETY'.
But, I am not sure how this is indicated.

Can you help me to learn more?

(Other definitions for entirety that I've seen before include "The lot" , "Sum" , "Absoluteness" , "Totality" , "Whole" .)

I've seen this clue in The Globe and Mail.

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