Old Spanish coin (6)
(Other definitions for peseta that I've seen before include "Old money - see Pat (anag)" , "little cash is required" , "Old tender" , "Old Spanish coin" , "Pre-Euro Spanish currency" .)
(Other definitions for piastre that I've seen before include "bit of money" , "Small amount of money" , "Former coin in some Middle Eastern countries" , "Foreign currency" , "Syrian money" .)