Start of many California place names (3)
I believe the answer is:
san
'start of many california place names' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for san that I've seen before include "School medical facility" , "Hospital (abbrev.)" , "sickbay" , "Japanese title" , "South African bushman; convalescent hospital" .)