In the pubs of Joyce's time, a "curate" was a bartender. The
name comes from the Catholic church, and puns on the notion of
being a servant or server.
The Catholic church delivers the cure animarum, the
cure or care of souls. A curate is a person charged with this
responsibility, so parish priests are often called curates, as
in the French title curé. But in England and Ireland
the term typically refers to priests who assist the parish
priest—junior members of the profession, assistants to the
celebrants of the Mass.
In Calypso Bloom imagines Larry O'Rourke "watching
the aproned curate swab up with mop and bucket,"
and then thinks of these employees "Coming up
redheaded curates from the county Leitrim, rinsing
empties and old man in the cellar. Then, lo and behold, they
blossom out as Adam Findlaters
or Dan Tallons." The analogy between a clerical vocation
and a career in alcohol-delivery is clear: pay your dues,
faithfully serve the mother-institution, and before too long
you can have your own establishment.
In Lestrygonians Bloom is respectfully addressed
as "sir" by the "curate" in Davy Byrne's, who
serves Bloom his cheese sandwich and glass of burgundy. Davy
Byrne himself chats with his customers, but does not do the
serving.