Roar with laughter in Washington at party for uncompromising banks all getting backed (6)
I believe the answer is:
guffaw
'roar with laughter' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for guffaw that I've seen before include "Roar of laughter" , "Laugh boisterously" , "A loud raucous laugh" , "coarse laughter" , "way of expressing amusement" .)