Helpful first violinist?

• Case: it involves singular person on the fiddle?
• Musician
• Ancillary role of 2 Down
• Tuba player, e.g.
• Someone who plays a musical instrument (as a profession)

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ All the instrumentalists, of course, weave solos through this fabric of sustained notes, but the focal point is Threadgill. ▪ First, the ballet livrets of this period treat the instrumentalists as members of discrete groups. ...

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 .

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Instrumentalism \In`stru*men"tal*ism\, n. (Philos.) The view that the sanction of truth is its utility, or that truth is genuine only in so far as it is a valuable instrument. -- In`stru*men"tal*ist , n. Instrumentalism views truth as simply the value belonging ...