Pure run on European currency (5)
I believe the answer is:
rupee
'currency' is the definition.
(eg currency of India)
'pure run on european' is the wordplay.
'run' is an anagram indicator.
'on' indicates putting letters inside (as in clothing 'on' a person).
'european' becomes 'E' (abbreviation e.g. EU).
'pure' is an anagram of 'rupe'.
'rupe' placed around 'e' is 'RUPEE'.
(Other definitions for rupee that I've seen before include "India's currency" , "Unit of money in India" , "foreign money" , "Lots of pies" , "Indian bread" .)