Pure form of Eastern currency (5)
I believe the answer is:
rupee
'currency' is the definition.
(eg currency of India)
'pure form of eastern' is the wordplay.
'form of' indicates anagramming the letters.
'eastern' becomes 'e'.
'pure' is an anagram of 'rupe'.
'rupe'+'e'='RUPEE'
(Other definitions for rupee that I've seen before include "Lots of pies" , "11 [LOLLY] in Kerala" , "little money abroad" , "Indian currency unit" , "Unit of money in India" .)