1) Business relation 2) Clientele 3) Dependency 
the whole number of one's clients
• (n.) A body of clients. • (n.) State of being client.
Cli'ent·age noun 1. State of being client. 2. A body of clients. E. Everett. 
[n] - relation of a client to a patron
clientage 1. A relation of a client to a patron. 2. A social system in which free commoners receive the patronage of wealthy or influential aristocrats. It was common in ancient Rome and has become a feature of some modern societies.
noun relation of a client to a patron
a body of clients; clientele. · the relationship of a client to a patron; dependency.