Sound upset, drunk, staggering (10)

I believe the answer is:

stupendous

'staggering' is the definition.
(thesaurus)

'sound upset drunk' is the wordplay.
'drunk' indicates an anagram.
'sound'+'upset'='soundupset'
'soundupset' anagrammed gives 'STUPENDOUS'.

(Other definitions for stupendous that I've seen before include "Astounding" , "Extremely impressive" , "Phenomenal" , "Astoundingly huge" .)

I've seen this clue in The Independent.

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