a businessperson who works alone
Since Carruth is a one-man band and autodidact, he learned how to create the special effects for the creature himself.
Until now, Trump has been “a one-man band,” according to the source close to Trump who does not want to be identified.
She sits up tall and strikes up her one-man band of sing-song sound.
An enterprise, business, etc, controlled by one person: The company had previously been run as a ''one-man show'' (entry form 1921+, variant 1938+)