Someone who plays a musical instrument (as a profession)

• One just plays at work
• Case: it involves singular person on the fiddle?
• Ancillary role of 2 Down
• Tuba player, e.g.
• Helpful first violinist?

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Instrumentalist \In`stru*men"tal*ist\, n. One who plays upon an instrument of music, as distinguished from a vocalist .

Wiktionary Word definitions in Wiktionary
n. One who plays a musical instrument, as distinguished from a vocalist

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1823, from instrumental in the musical sense + -ist .