Banff originally in with it, a Canadian province (7)
I believe the answer is:
alberta
'canadian province' is the definition.
(Alberta is an example)
'banff originally in with it a' is the wordplay.
'originally' indicates taking the first letters.
'in' is an insertion indicator.
'with it' becomes 'alert' (I've seen this in another clue).
The initial letter of 'banff' is 'b'.
'b' going inside 'alert' is 'albert'.
'albert'+'a'='ALBERTA'
(Other definitions for alberta that I've seen before include "Einstein" , "Beat Lar up in Canada" , "part of Canada" , "Banff province" , "Bale rat out of Canada" .)