Threshing implement (5)
I believe the answer is:
flail
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">threshing implement</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for flail that I've seen before include "Weapon; swing wildly" , "Wave about wildly" , "Threshing implement" , "Grain thresher" , "Thresh about" .)