Comedian to laugh uproariously (6)
I believe the answer is:
scream
I believe this is a double definition.
'comedian' is the first definition.
(I've seen this before)
'to laugh uproariously' is the second definition.
(Other definitions for scream that I've seen before include "Yell in fear" , "Riot" , "Sound terrified" , "painting" , "'Loud, high-pitched cry (6)'" .)