Sidesplitters (5)
I believe the answer is:
riots
'sidesplitters' is the definition.
('riot' can be a synonym of 'sidesplitter')
This is the entire clue.
(Other definitions for riots that I've seen before include "Public disturbances" , "Violent disturbances" , "Protests" , "Wild disturbances by crowds" , "Acts of violence by unruly mobs" .)