Bolt securer
I believe the answer is:
nut
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bolt securer</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 nut that I've seen before include "Large, hard-shelled seed" , "Hard fruit or informal lunatic" , "Mechanical fastener" , "Combines with bolt to secure" , "One securing bolt" .)