We initially welcome song and dance performance without uniform that's quaint (9)

I believe the answer is:

whimsical

'quaint' is the definition.
(thesaurus)

I can't explain the rest of the clue.

(Other definitions for whimsical that I've seen before include "Fanciful, fantastical" , "Mischievous" , "Playfully quaint" , "Quirky" , "Capricious" .)

I've seen this clue in The Guardian.

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