Position King overlooked in a certain European subject (8)
I believe the answer is:
liegeman
'subject' is the definition.
(historical subject of a lord)
'position king overlooked in a certain european' is the wordplay.
'position' becomes 'lie' (lie can mean to place or position).
'king' becomes 'R' (abbreviation for rex, king in Latin).
'overlooked in' is a deletion indicator.
'a certain european' becomes 'German' (Germany is in Europe).
'german' with 'r' taken away is 'geman'.
'lie'+'geman'='LIEGEMAN'
(Other definitions for liegeman that I've seen before include "Loyal follower" , "A loyal person" , "Vassal, subject" , "Person serving lord" .)