It’s been some time since Roy Clark could bound out onto a stage like a puppy just turned loose, brandishing an electric guitar and a joyous smile, ready to captivate a crowd with his personality and talent. Friday night, it took him a number of slow and careful steps, and the assistance of a cane and a couple of colleagues, to make his way to a chair on the small stage of Tulsa’s Spotlight Theater. Once he settled himself, Clark said, “I have to be careful I don’t...,” and he gave audience a comically knowing look, “...make an entrance. Which...