Old coin for royal symbol (5)
I believe the answer is:
crown
I believe this clue is a triple definition!
'old coin' is the first definition.
(I've seen this before)
'for royal' is the second definition.
(thesaurus)
'symbol' is the third definition.
(I know that Crown is a type of symbol)
(Other definitions for crown that I've seen before include "Coronet" , "piece of tooth" , "The sovereign" , "Coin; royal headgear" , "Headdress, coin" .)