Leaders suggest England's ruled by a European (4)
I believe the answer is:
serb
'a european' is the definition.
(person from Serbia)
'leaders suggest england's ruled by' is the wordplay.
'leaders' indicates taking the first letters.
The initial letters of 'suggest englands ruled by' is 'SERB'.
(Other definitions for serb that I've seen before include "Eg, native of Belgrade" , "Eastern European" , "One from Belgrade" , "Balkan native" , "A European national" .)