n [ usu sing ] ( BrE )
an area outside a city, where rich people live in large expensive houses. Many of them work in the city as highly paid professional people, e.g. stockbrokers (= people who buy and sell shares in companies on behalf of other people). Most people think of the typical stockbroker belt as Surrey , south-west of London, but the phrase can be used to refer to any expensive area outside a city:
They bought a large detached house in the heart of the stockbroker belt.