Tool for nuts (7)
I believe the answer is:
spanner
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tool for nuts</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 spanner that I've seen before include "Nut tightener" , "Tool, often adjustable" , "Hand tool to grip and turn" , "Nut-tightening tool" , "murder weapon" .)