Old gold coin (5)
'old gold coin' is the definition.
(old European coin)
This is the entire clue.
(Other definitions for ducat that I've seen before include "Mad; fruit" , "Antique coin" , "Former European gold coin" , "piece of gold" , "Former Italian gold coin" .)
(Other definitions for moidore that I've seen before include "old money" , "old coin" , "European currency, as of old" , "Portuguese currency" , "Former Portuguese gold coin" .)
'old gold coin' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for doubloon that I've seen before include "Former Spanish gold coin" , "Old Spanish gold coin" , "Another old Spanish coin" , "Ancient Spanish gold coin" .)