Judge banking fraud by extremely unfair account provider (9)
I believe the answer is:
raconteur
'account provider' is the definition.
(a raconteur provides stories or accounts of things)
'judge banking fraud by extremely unfair' is the wordplay.
'judge' becomes 'rate' (rating is a kind of judging).
'banking' is an insertion indicator.
'fraud' becomes 'con' (con is a kind of fraud).
'by' means one lot of letters go next to another.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'unfair' with its middle removed is 'ur'.
'rate' going around 'con' is 'raconte'.
'raconte'+'ur'='RACONTEUR'
(Other definitions for raconteur that I've seen before include "A skilled story teller" , "A good teller of tales" , "Anecdotist" , "Skilful teller of anecdotes" , "One spinning yarns" .)