Oxen's harness (4)
I believe the answer is:
yoke
'oxen's harness' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yoke that I've seen before include "Oppressive rule" , "get loaded and pull?" , "Wooden crosspiece or burdensome restraint" , "Oxen harness" , "Bond of servitude" .)