Financier having 100 for northern supporter (6)
I believe the answer is:
backer
'northern supporter' is the definition.
'backer' can be an answer for 'supporter' (backer is a kind of supporter). I'm unsure of the 'northern' bit.
'financier having 100' is the wordplay.
'financier' becomes 'baker' (I am not sure about this - if you are sure you should believe this answer much more).
'having' is an insertion indicator.
'b00' becomes 'c' (roman numeral).
'baker' enclosing 'c' is 'BACKER'.
'for' is the link.
Can you help me to learn more?
(Other definitions for backer that I've seen before include "Patron or supporter" , "Person supporting another financially" , "Financial supporter" , "A supporter or a betting man" , "Angel" .)