one-man band

noun3

1. •
   A musician who plays several musical instruments at once.
2. •
   A band in which the frontman does most of the work and is the spotlight or the center of attention, usually to the detriment of other band members.
3. •
   An organisation or business that is effectively run by only one person.

   • The corporation he will someday inherit—growing, churning—won't work as a one-man band. — 2007