ply for hire
To seek out or try to engage new customers. Said especially of taxi services. Primarily heard in UK. The city council has introduced new measures to crack down on the number of taxis allowed to stop outside of pubs and theatres plying for hire.
ply for ˈhire/ˈtrade/ˈbusiness
(British English) look for customers, passengers, etc. in order to do business: There are plenty of taxis plying for hire outside the theatre.