Bicycle wheel radius (5)
I believe the answer is:
spoke
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bicycle wheel radius</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 spoke that I've seen before include "Radius" , "Rung" , "addressed" , "gave a lecture" , "Wheel's radial member" .)