Mammoth, kitten or mouse innards (8)

I believe the answer is:

enormous

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'mammoth' is the definition.
(synonyms)

'kitten or mouse innards' is the wordplay.
'ENORMOUS' is hidden within the letters.
However, I am not sure how this is indicated.

Can you help me to learn more?

(Other definitions for enormous that I've seen before include "Extremely large" , "Gross" , "Giant" , "Extraordinarily large" , "Vast" .)

I've seen this clue in the Sydney Morning Herald.

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