Actual kingdom miles away (4)
I believe the answer is:
real
'actual' is the definition.
(I know that actual can be written as real)
'kingdom miles away' is the wordplay.
'kingdom' becomes 'realm' (kingdom is a type of country or realm).
'miles' becomes 'm' (common abbreviation).
'away' suggests deleting specific letters.
'realm' with 'm' taken out is 'REAL'.
(Other definitions for real that I've seen before include "foreign currency" , "---- Madrid, Spanish football club" , "Actual, existing" , "Actual, not imaginary" , "The old coin actually exists" .)