What is the name of the kung-fu movie about a man on a quest to find Zeton?

Hello

You are lucky that I know about the movie and the correct spelling of Zetan

The movie is called Circle of Iron.

It's a 1978 martial arts and fantasy film co-written by Bruce Lee who intended to star in the film , though as most know died before it's production.

The movie begins with a martial arts tournament, in which fighters are competing for the right to begin a quest to challenge Zetan.

Anyway hope that answer your question and if it does mark this helpful.