gun-for-hire

A contract killer.

A contractor.

After months of bitter disagreements and legal back-and-forth, he had finally given up and struck out on his own, but he'd met with a string of bad luck—a client who refused to pay, a flood, a false insurance claim—and he'd had to shut up shop; now he was working for a big construction firm as a gun for hire and telling anybody who would listen what a rotten hand he had been dealt.