A new bill in California refers to state over the American border
I believe the answer is:
canada
'refers to state over the american border' is the definition.
I can't tell whether this definition defines the answer.
'a new bill in california' is the wordplay.
'a new' becomes 'an' (I've seen this in other clues).
'bill' becomes 'ad' (advertisement stuck on wall).
'in' indicates putting letters inside.
'california' becomes 'ca'.
'an'+'ad'='anad'
'anad' placed within 'ca' is 'CANADA'.
Can you help me to learn more?
(Other definitions for canada that I've seen before include "N American country" , "Second-largest country in the world by area" , "Queen Elizabeth is it's head of state" , "Large country" , "North American nation" .)