Small-time (adjective)

1. Of limited importance or scale; insignificant or minor.
2. Having little or no success; amateurish.

Origin:

This phrase is thought to have originated in the early 1900s and may have originated in the criminal underworld, where it referred to petty criminals or low-level operations. the exact origin is unclear.

Examples:

1. He's a small-time crook who's never been able to pull off a big heist.
2. She's a small-time actress who has never made it to the big leagues.
3. The company was a small-time operation that couldn't compete with the larger corporations.
4. He was a small-time gambler who never won big.
5. She was a small-time writer who never found much success.