In part one of this two part series, I wrote about personal patronage in the ancient and modern context. Today, I want to talk about professional patronage (i.e. Apollon as the patron of the arts, and thus prayed to by artists). Personally, I think the only thing that professional patronage shares with the practice of personal patronage is its name--and we will get to that in a second.
The interesting thing is that none of the academic sources at my disposal make mention of this practice under the term 'patronage'. Patronage in the context of ancient Hellas seems to focus on the non-lineal bond between two people--a patron who took care of a client or slave in a material, financial, or emotional way. 'Patron' to mean the support, encouragement, or privilege that a deity bestows upon those practicing a profession or living in a city is a Christian term, which refers to patron saints. Patron saints are regarded as the tutelary spirits or heavenly advocates of a nation, place, craft, activity, class, clan, family, or person. Taking this description would give you, for example, Athena as the patron of Athens--but outside of Christianity, the proper term is 'tutelage'; a tutelary deity.
A tutelary, or tutelar, deity is 'a guardian, patron, or protector of a particular place, geographic feature, person, lineage, nation, culture or occupation'. Both tutelary and tutelar can be used as either a noun or an adjective. As such, Athena is the tutelary Goddess of Athens, or the tutelar of Athens--but because we are so used to 'patron(ess)', 'tutelar' does not have quite the same ring to it.