Purchaser (5)
'purchaser' is the definition.
(I know that purchaser can be written as buyer)
This is all the clue.
(Other definitions for buyer that I've seen before include "Caveat emptor - . . . . . beware" , "One who seeks to purchase" , "customer" , "Selector of stock" , "Shopper" .)
(Other definitions for owner that I've seen before include "Person with legal title to something" , "The one in lawful possession" , "Person having property" , "Title-holder" , "The person in lawful possession" .)