Speed at which one can give and receive money (8,4)
I believe the answer is:
exchange rate
'speed at which one can give and receive money' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'speed at which one' is the wordplay.
'speed' becomes 'rate' (the speed at which something happens).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'which one' becomes 'exchange' (I can't justify this - if you can you should give a lot more credence to this answer).
'rate' after 'exchange' is 'EXCHANGE RATE'.
Can you help me to learn more?
(Other definitions for exchange rate that I've seen before include "Price of one currency in another" , "Figure used when converting currency" , "various notes in a relationship?" .)