Helicopter blade (5)
I believe the answer is:
rotor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">helicopter blade</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for rotor that I've seen before include "It lifts helicopter" , "Revolving arm in machine" , "Mechanical turning part" , "Revolver" , "Revolving blade (as on helicopter)" .)