Trouble composing a trio (4)

I believe the answer is:

riot

'trouble' is the definition.
(thesaurus)

'composing a trio' is the wordplay.
'composing' indicates an anagram.
'trio' is an anagram of 'RIOT'.

(Other definitions for riot that I've seen before include "Lavish display (of colour)" , "Civil disorder" , "Uproar" , "Wild revelry" , "Take to the streets" .)

I've seen this clue in the Evening Standard.

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