Feudal worker (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">feudal worker</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for serf that I've seen before include "Person bound to the land and owned by a feudal lord" , "Feudal subject" , "(In the Middle Ages) someone bound to the land" , "Thrall" , "Slave" .)