Scuffle (6)
'scuffle' is the definition.
(I know that scuffle can be written as tussle)
This is the entire clue.
(Other definitions for tussle that I've seen before include "Fight vigorously" , "Go at it" , "A struggle or conflict" , "'Scuffle, rough-and-tumble (6)'" , "scrap" .)
(Other definitions for ruckus that I've seen before include "Rumpus. commotion" , "Row or commotion" , "Uproar - noisy disturbance" .)