Unwanted discharge of fluid (7)
I believe the answer is:
leakage
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unwanted discharge of fluid</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 leakage that I've seen before include "Percolation" , "Accidental spill" , "Liquid/gas accidentally lost" , "Escape of liquid or gas - or confidential information" , "Accidental escape (of a liquid or gas)" .)