Party with any number under canvas makes one unhappy (12)

I believe the answer is:

discontented

'one unhappy' is the definition.
(thesaurus)

'party with any number under canvas' is the wordplay.
'party' becomes 'disco' (I've seen this before**).
'with' says to put letters next to each other.
'any number' becomes 'n' (I've seen this in other clues).
'under canvas' becomes 'tented' (I've seen this before).
'disco'+'n'+'tented'='DISCONTENTED'

'makes' is the link.

(Another definition for discontented that I've seen is " Restless and unhappy".)

I've seen this clue in The Telegraph.

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