Name on envelope is American banker, receiving treat (9)
I believe the answer is:
addressee
'name on envelope' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for addressee that I've seen before include "The person to whom letter is delivered" , "Recipient of mail" , "Recipent" , "Recipient of post" , "Person named on an envelope" .)