... reportedly arrests Europeans (6)
I believe the answer is:
czechs
'europeans' is the definition.
'reportedly arrests' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'arrests' becomes 'checks' ('check' can be a synonym of 'arrest').
'checks' sounds like 'CZECHS'.
(Other definitions for czechs that I've seen before include "Eg, Prague natives" , "Citizens of a republic" , "Slavs" , "Nationality of citizens of Prague" .)