Kingdom (5)
'kingdom' is the definition.
(kingdom is a type of country or realm)
This is the entire clue.
(Other definitions for realm that I've seen before include "Knowledge base" , "Area of interest/activity" , "Peers are possessed by this" , "Province" , "World" .)
'kingdom' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for empire that I've seen before include "Over which 23 down rules" , "Widespread political or industrial organisation" , "Wide dominion" , "Former British rule" , "Eg Holy Roman, British or Ottoman" .)