Nut-turning tool (7)
I believe the answer is:
spanner
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">nut-turning tool</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 spanner that I've seen before include "Tool for gripping and turning" , "Bad thing to have in the works!" , "Nut-tightening tool" , "Nut turner" , "Tool for tightening or loosening" .)