Brake element (4)
I believe the answer is:
disc
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">brake element</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 disc that I've seen before include "Circle" , "Flat thin round object" , "Capital of India" , "Forty-five" , "put on by jockey?" .)