Revolving part (5)
I believe the answer is:
rotor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">revolving part</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 rotor that I've seen before include "Hub with radiating blades" , "Part of, eg, a motor" , "Turning part of machine - a palindrome" , "Revolving blade (as on helicopter)" , "Helicopter supporter" .)