Both Uses of

patron
in
The Sunlight Dialogues

He'd suffered the usual brainless complaints of diner patrons, no two of whom meant the same thing by "rare" or "medium" when they ordered a T-bone steak, and along with that the eternal nagging of the owner's wife, a short-tempered middle-aged Irish lady who blamed her flare-ups, afterward, on the fact that she was a redhead, which she was not.†
Chpt 5

He bought a Buffalo Evening News with the air of a patron of the arts, though Louise would have a copy at the house already, and he unfolded it with the detached curiosity of a stockbroker as he let himself into the M&T lobby.†
Chpt 8 *

Definitions:

(1) (patron as in: a patron of the arts)
a regular customer; or someone who gives money or support to an organization, cause, or person
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

In ancient Roman history, patron referred to the more powerful person in a complex client-patron relationship. The term is still used in some cultures today to describe a property owner who is in charge of workers.

Also see patron saint.

Much more rarely, a patron is the proprietor of an inn.