Senior coppers and judge secure noble financial arrangement (8,4)

'financial arrangement' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.

'senior coppers and judge secure noble' is the wordplay.
'senior coppers' becomes 'dis' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'and' is a charade indicator (letters next to each other).
'judge' becomes 'rate' (rating is a kind of judging).
'secure' is an insertion indicator (inserted letters are secured inside).
'noble' becomes 'count' (count is a type of aristocrat).
'dis'+'rate'='disrate'
'disrate' enclosing 'count' is 'DISCOUNT RATE'.

Can you help me to learn more?