The verb "to busk" has multiple senses:

To entertain (or in some usage sell wares) in public, possibly in bars, on streets, in transit stations, open markets,  parks, etc.

To make ready, prepare, or dress.

To generally go about or direct one's course.

To, in a nautical sense, tack or cruise about. Possibly in some usage with the literal or figurative sense of being pirate-like.

The dress/prepare sense could be related to noun busk which is a type of support (historically whalebone) used in corsetry.

The general and nautical sense of busk may relate to various Romance language verbs (busquer, buscar, buscare) indicating seeking or searching.

The entertaining sense could combine the Romance roots with Celtic roots words meaning to gain victory or win.

But it's interesting that buskers could be understood to combine all these senses, as independent traveling performers, theatrically dressed, seeking payment.