One introduces medal impressed by Europeans (5)
I believe the answer is:
emcee
'one introduces' is the definition.
(an emcee introduces people on stage)
'medal impressed by europeans' is the wordplay.
'medal' becomes 'mc' (I can't justify this - if you can you should believe this answer much more).
'impressed by' indicates putting letters inside.
'europeans' becomes 'EEE' (three abbreviations for European).
'mc' put within 'eee' is 'EMCEE'.
(Other definitions for emcee that I've seen before include "A host of Americans" , "Compre" , "One presents" , "Someone presenting" , "MC" .)