Reasons copper’s got to arrest E European dictator (9)
I believe the answer is:
ceausescu
'european dictator' is the definition.
(Romanian dictator Nicolae Ceausescu)
'reasons copper's got to arrest e' is the wordplay.
'reasons' becomes 'causes' (the reasons for something).
'copper' becomes 'Cu' (chemical symbol).
'got to arrest' indicates putting letters inside (inserted letters are held or arrested).
'causes'+'cu'='causescu'
'causescu' going around 'e' is 'CEAUSESCU'.
(Other definitions for ceausescu that I've seen before include "Repressive president" , "Deposed Romanian leader" , "Communist president deposed and shot in 1989" , "Romanian Communist leader, killed 1989" .)