Tree to come down in Californian city (7)
I believe the answer is:
oakland
'californian city' is the definition.
'tree to come down' is the wordplay.
'tree' becomes 'oak' (oak is a kind of tree).
'to come down' becomes 'land' (I've seen this before).
'oak'+'land'='OAKLAND'
'in' is the link.
(Other definitions for oakland that I've seen before include "Californian city on the opposite side of the Bay from San Francisco" , "Port on San Francisco Bay" , "US city" , "Seaport near San Francisco, and Raiders" , "US port" .)