Junior corporation? (5)

I believe the answer is:

tummy

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This might be a double definition.

'junior' is the first definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.

'corporation?' is the second definition.
(synonyms)

Can you help me to learn more?

(Other definitions for tummy that I've seen before include "Paunch" , "middle" , "Stomach, abdomen" , "Belly" , "Stomach (informal)" .)

I've seen this clue in the Evening Standard.

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