It may go up - everybody's in favour (7)

I believe the answer is:

balloon

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'it may go up' is the definition.
The definition suggests a singular noun which matches the answer.

'everybody's in favour' is the wordplay.
'everybody' becomes 'all' (all people).
'in' is an insertion indicator.
'favour' becomes 'boon' (I've seen this before).
'all' going within 'boon' is 'BALLOON'.

Can you help me to learn more?

(Other definitions for balloon that I've seen before include "Inflatable - rapidly expand" , "Brandy glass" , "Air transport" , "See 21" , "Inflatable thin rubber ball" .)

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

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