Unpleasantness (9)
I believe the answer is:
nastiness
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unpleasantness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(nastiness is a kind of unpleasantness)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nastiness that I've seen before include "repugnance" , "ill humour" , "Unpleasant behaviour" , "hostility" , "Pollution" .)