Oppressive burden (4)
I believe the answer is:
yoke
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">oppressive burden</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for yoke that I've seen before include "Frame joining draught oxen at the necks" , "Coupling" , "Bond of servitude" , "Oppressive power" , "Burdensome restraint or oppression" .)