Tyrant from the French bank (6)
I believe the answer is:
despot
'tyrant' is the definition.
(I know that tyrant can be written as despot)
'from the french bank' is the wordplay.
'from the french' becomes 'des' (I've seen this in other clues).
'bank' becomes 'pot' (I am not sure about this - if you are sure you should believe this answer much more).
'des'+'pot'='DESPOT'
Can you help me to learn more?
(Other definitions for despot that I've seen before include "Gaddafi, say" , "Person with more than enough power" , "Cruel and oppressive ruler" , "Cruel and oppressive dictator" , "who treats others badly?" .)