Roar with laughter (6)
I believe the answer is:
guffaw
'roar with laughter' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for guffaw that I've seen before include "A loud uninhibited laugh" , "Roar of laughter" , "Laugh loudly" , "coarse laughter" , "Crude and boisterous laugh" .)