Tesla rival (6)
I believe the answer is:
edison
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tesla rival</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 edison that I've seen before include "No side to this american inventor" , "scientist" , "Thomas ......, famous American inventor" , "Thomas Alva ......, great American inventor" , "Inventor's" .)