Not set (5)
I believe the answer is:
runny
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not set</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 runny that I've seen before include "Molten" , "(Of liquid) thin" , "Tending to flow" , "More liquid than usual" , "Fluid" .)