If you’ve gone out for dinner on East Bay Street on a weekend night, you’ve probably seen Clarence McDonald perched behind his xylophone, playing along to back-tracks of pop songs from his boombox and occasionally blowing into a melodica for variety’s sake. A veteran of the Charleston street music scene, he previously played bass with a touring soul band during the ’70s and traveled around the world in the Army during the ’80s. Back in Charleston, he has worked as a grocery bagger and enrolled in Trident Technical College’s Clemente Courses for adult education, where he returned to serve as a volunteer for later classes. When we hear him playing, we always stop to listen — and we leave a tip. In a town where police have been known to chase performers off of the Market, gems like Clarence can use all the help they can get.