When halved, list Ray's old foreign currency (4)
I believe the answer is:
lira
'old foreign currency' is the definition.
(former currency of Italy)
I can't explain the remainder of the clue.
(Other definitions for lira that I've seen before include "Former unit of currency in Italy" , "Unit of money for 26 across" , "Old Spanish currency" , "Former Italian currency unit" , "Pre-euro currency unit in Italy" .)