one-man band 
noun
1A street entertainer who plays many instruments at the same time.From its humble origins as the one-man band of Dallas indie rocker John Dufilho, the Deathray Davies has released a handful of colorfully named albums....
- I am totally different from everyone else in the game because not only do I rap, I also produce, play musical instruments and sing which makes me literally, a one-man band.
- If they bothered to turn around, they saw a monotonous singer, a cacophonous one-man band, a juggler of little note.
1.1A person who runs a business alone: as a one-man band his overheads were negligible...
- In a similar vein, one-product companies, one-client businesses and one-man bands are rarely good long-term stock market bets.
- At present the French one-man band running the dive operation in Fare is a little lackadaisical.
- A business that started as a one-man band and today employs 43 staff is now poised for the next stage of growth.