Doctor sure’s confused receiving Portuguese coin upfront as refund (9)
I believe the answer is:
reimburse
'refund' is the definition.
(reimbursing is a kind of refunding)
'doctor sure's confused receiving portuguese coin upfront' is the wordplay.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'confused' indicates an anagram.
'receiving' is an insertion indicator.
'portuguese coin' becomes 'rei' (historical monetary unit of Portugal).
'upfront' says to put letters next to each other (some letters go in front of others).
'sure' anagrammed gives 'urse'.
'mb' put into 'urse' is 'mburse'.
'mburse' after 'rei' is 'REIMBURSE'.
'as' is the link.
(Other definitions for reimburse that I've seen before include "Pay back any expenses incurred" , "Repay (a sum of money)" , "Financially compensate" , "refund" , "Repay - reuse brim" .)