Rotating part (3)
I believe the answer is:
cam
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rotating part</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for cam that I've seen before include "Rotating part in machine; river" , "Bump on a shaft for pushing another shaft" , "Projection on a rotating shaft in contact with another part" , "Projection on rotating cylinder" , "Rotating mechanism" .)