Feudal retainer (6)
I believe the answer is:
vassal
'feudal retainer' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for vassal that I've seen before include "Feudal underling" , "A humble servant as of 9 Down" , "One owing fealty" , "Feudal subordinate" , "Slave" .)