Stupid, happy band (10)

I believe the answer is:

blithering

'stupid' is the definition.
(I've seen this before)

'happy band' is the wordplay.
'happy' becomes 'blithe' (I've seen this before).
'band' becomes 'ring' (ring is a kind of band).
'blithe'+'ring'='BLITHERING'

(Other definitions for blithering that I've seen before include "Foolish" , "Stupid" , "talking foolishly" , "Contemptible" .)

I've seen this clue in The Telegraph.

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