If this was a sentimental frame so it was worth the effort, I would start by bending the ear back as best as possible. Next using a big rosebud flame, I’d remove the seat binder cluster. Shaping a piece of 1 1/4” OD with .058” walls to slide over the extended seat tube to just avoid running into the stays. This would take some blacksmithing. I’d drill a small hole at the end of the crack and fill it with brass. Silver the sleeve and brass braze a new binder.