An amusement (noun) is an act of being a muse, regardless of whether that that act is done part-time or full-time and regardless of whether the full- or part-time muse is employed by a musing company or works freelance. An amusement can even be performed as a one-time event, or it might be part of a life-long (except, possibly, infancy and/or toddlerhood) musing career—or anything in between.
Performing an amusement for, say, a writer with writer’s block or a composer who, for whatever reason, is not notable at the moment is a noble gesture. Amusements have, through the works of art, music and literature created by people who were inspired by an amusement, lightened many hearts and uplifted many souls over the ages.
Then again, it typically doesn’t attract much money, so you might not want to take up being a muse as a career. It might be better to consider doing it solely as a hobby or as a second job to earn some spare change, possibly by delivering amusements on street corners.