A very strong beam reveals disturbance (6)
I believe the answer is:
affray
'disturbance' is the definition.
(synonyms)
'a very strong beam' is the wordplay.
'very strong' becomes 'ff' (musical abbreviation for fortissimo, 'very strong').
'beam' becomes 'ray' (synonyms).
'a'+'ff'+'ray'='AFFRAY'
'reveals' acts as a link.
(Other definitions for affray that I've seen before include "A fight or riot in public" , "commotion" , "Noisy disturbance" , "Breach of the peace by public rioting" , "Disturbance in public place" .)