Busk: to play music or perform entertainment in a public place, usually while soliciting money. [Earlier, to be an itinerant performer, probably from busk, to go about seeking, cruise as a pirate, perhaps from obsolete French busquer, to prowl, from Italian buscare, to prowl, or Spanish buscar, to seek, from Old Spanish boxcar.]
Reference: http://www.thefreedictionary.com/busking