carriage trade

skin trade

The sex industry

take out in trade

To accept repayment of a debt in the goods or services in which the debtor deals, rather than in money.

tools of trade

The items and equipment that a person uses in the course and scope of their profession, trade, or occupation.

trade hands

To change ownership.

trick of the trade

A shortcut or other quick, or very effective way of doing things, that professional workers learn from experience.