Go fast (6)
I believe the answer is:
streak
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go fast</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 streak that I've seen before include "series of lucky wins" , "Spell (of good luck)" , "Long thin mark" , "Flash of colour - run naked" , "feature of bacon" .)