Hill over Canadian city (7)
I believe the answer is:
toronto
'canadian city' is the definition.
(I've seen this before)
'hill over' is the wordplay.
'hill' becomes 'tor' (tor is a kind of hill).
'over' becomes 'onto'.
'tor'+'onto'='TORONTO'
(Other definitions for toronto that I've seen before include "Canadian city" , "Ontarian capital" , "North American city" , "major city" , "place on Lake Ontario" .)