Pinion's partner (4)
I believe the answer is:
rack
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pinion's partner</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rack that I've seen before include "Cause of anguish" , "Instrument of torture, stretched its victims" , "Old instrument of torture" , "Rail for torture" , "Driving mist" .)