Heard man request a payment method (4,5)
I believe the answer is:
mail order
'method' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'heard man request a payment' is the wordplay.
'heard' indicates a 'sounds like' (homophone) clue.
'man' becomes 'male'.
'request a payment' becomes 'order' (I can't explain this - if you can you should give a lot more credence to this answer).
'male' sounds like 'mail'.
'mail'+'order'='MAIL-ORDER'
Can you help me to learn more?
(Other definitions for mail order that I've seen before include "Buying by post" , "One way to get delivery" , "that one's sent for?" , "Shopping by post" , "Way to shop" .)