Motorcycle sport (8)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">motorcycle sport</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 speedway that I've seen before include "Dirt track motorcycle racing" , "SPORT/GAME" , "Stadium for motorcycle racing" , "Form of motorcycle racing" , "Motor sport" .)