consultant

act as

The architect agreed to act as a consultant on the new building project.

bring in, employ (sb as), engage (sb as), hire (sb as), use

The company decided to hire a consultant to help them improve their sales strategy.

~ in

My sister works as a consultant in environmental health and regularly advises companies on safety practices.

~ on

She hired a consultant on marketing strategy to help improve the company's sales.

~ to/with

A management consultant with our organization helped us improve our business processes.

hospital, NHS

My uncle works as an NHS consultant helping patients with heart problems.

~ in

My sister works as a consultant in marketing for several technology companies.