Highly unpleasant (5)
I believe the answer is:
nasty
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">highly unpleasant</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 nasty that I've seen before include "Vile" , "Disgusting" , "Foul" , "Highly repugnant" , "grave" .)