Snow runner (3)
I believe the answer is:
ski
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">snow runner</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 ski that I've seen before include "Glide or race across snow with feet attachments" , "Engage in a winter sport" , "Go downhill rapidly" , "Winter sport equipment" , "Mountain runner" .)