Snake in the Monkey's Shadow(1979)

Overview:

A young peasant boy who is bullied by local noblemen seeks to learn drunken boxing from the head of a local martial arts school. When the boy beats up his previous tormentors, the nobles patriarch challenges the boys teacher, the drunken master, who defeats the lot of them. Embarrased, the nobles retain two hired snake style killers. They kill everyone except the peasant boy.