One night in Montreal: I’ve come a long way south? (5)
I believe the answer is:
inuit
'montreal i've come a long way south?' is the definition.
I can't tell whether this defines the answer.
'one night' is the wordplay.
'one' becomes 'i' (Roman numeral).
'night' becomes 'nuit' (I can't explain this - if you can you should believe this answer much more).
'i'+'nuit'='INUIT'
'in' is the link.
(Other definitions for inuit that I've seen before include "A North American eskimo" , "Dwellers in the furthest north of America" , "Indigenous Greenlander" , "People living in the Arctic" , "short stay in Paris hotel?" .)