Boisterous laugh (6)
I believe the answer is:
guffaw
'boisterous laugh' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for guffaw that I've seen before include "Laugh boisterously" , "A loud vulgar laugh" , "A loud uninhibited laugh" , "coarse laughter" , "Laugh heartily" .)