Noisy riotous fight (5)
I believe the answer is:
melee
'noisy riotous fight' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for melee that I've seen before include "confused group" , "Fracas" , "A confused fight or muddle" , "Confused crowd" , "Noisy riotous fight" .)