A very loud fish creates a disturbance (6)
I believe the answer is:
affray
'a disturbance' is the definition.
(synonyms)
'a very loud fish' is the wordplay.
'very loud' becomes 'ff' (musical abbreviation).
'fish' becomes 'ray' (ray is a kind of fish).
'a'+'ff'+'ray'='AFFRAY'
'creates' is the link.
(Other definitions for affray that I've seen before include "commotion" , "Fracas, noisy fight" , "Fish; had an odour" , "Breach of the peace by public rioting" , "Breach of peace through public fighting" .)