Like an idiot in cheerful group? (10)

I believe the answer is:

blithering

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'like an idiot in' is the definition.
I can't judge whether this definition defines the answer.

'cheerful group?' is the wordplay.
'cheerful' becomes 'blithe' (similar in meaning).
'group?' becomes 'ring' (a ring is a criminal organisation).
'blithe'+'ring'='BLITHERING'

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

I've seen this clue in The Times.

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