Long thin mark (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">long thin mark</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for streak that I've seen before include "Spell (of good luck)" , "Run naked; long mark" , "Band of colour - run naked" , "Skater (anag.)" , "Run of luck" .)
(Other definitions for line that I've seen before include "classified information" , "Dress" , "short note" , "Wrinkle; row" , "Fill" .)