Da chu tou (1979)

When two acrobats are fired for fighting with punks in the audience, they go to live with an aunt who's being pressured to sell her house for a real estate development. The developer's nasty son, Lee Fu, decides to muscle the sale, and soon he's at war with the acrobats, plus their unlikely ally, an American named John who used to be Lee Fu's friend. The acrobats open a kung fu school, the scene of several battles with Lee Fu's thugs. A fight to the death, jail time, auntie's surprise decision, a budding acting career, a possessive girlfriend, a debilitating injury, a friendship that needs recalibrating, and Lee Fu's avenger are all in the mix before the end.