Confine to borders of Californian sage (4)
I believe the answer is:
cage
This could be a double definition.
'confine' is the first definition.
(caging is a kind of confining)
'borders of californian sage' is the second definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for cage that I've seen before include "Eg, aviary" , "he used to write down scores" , "Coop" , "US composer -- barred enclosure" , "Tffhe goal in ice hockey" .)