Buyer, client (8)
I believe the answer is:
customer
I believe this is a double definition.
'buyer' is the first definition.
(I've seen this in another clue)
'client' is the second definition.
(I know that client can be written as customer)
(Other definitions for customer that I've seen before include "The one who pays is always right" , "Person buying" , "Client (who's always right?)" , "Rail passenger, nowadays" , "Shop client" .)