Unhorse (8)
I believe the answer is:
unsaddle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unhorse</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for unsaddle that I've seen before include "tend horse" , "get kit off in stable" , "shift from mount" , "Throw" , "Remove the seat from a horse" .)