Unpleasant child (4)
I believe the answer is:
brat
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unpleasant child</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 brat that I've seen before include "Urchin" , "annoying young fellow" , "A spoiled, badly behaved child" , "Nasty little kid" , "Troublesome child" .)