Failing; deficiency (11)
I believe the answer is:
shortcoming
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">failing</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I have seen 'A failing ' mean 'shortcoming' so perhaps 'failing' could also mean 'shortcoming')</span><br/ ><br/ >'<span class="explanation-format__original">deficiency</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for shortcoming that I've seen before include "Weakness" , "A failing" , "drawback" , "Fault, defect" .)