Run of luck (6)
I believe the answer is:
streak
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">run of luck</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 "Stripe of contrasting colour" , "'Sudden flash, of lightning say (6)'" , "Run naked as stunt" , "trace?" , "Skater (anag.)" .)