Ancient Roman coins (9)
'ancient roman coins' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for denarii that I've seen before include "money from abroad" , "Bits" , "A lot of asses" , "Ancient Roman coins" , "22 [COINS]" .)
(Other definitions for sesterces that I've seen before include "Old money" , "Roman brass" .)