Spokes (5)
I believe the answer is:
radii
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">spokes</span>' is the definition.<br/ ><span class="explanation-format__explanation">('radius' can be a synonym of 'spoke')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for radii that I've seen before include "Lines drawn from a circle's centre" , "Halves of diameter" , "Lines from centre to perimeter of a circle" , "Two making up diameter" , "spoke with others" .)