Unit of resistance (3)
I believe the answer is:
ohm
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unit of resistance</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 ohm that I've seen before include "A little resistance" , "measure of resistance" , "SI unit of electrical resistance" , "Unit of electrical resistance (3)" , "lawmaker" .)