Horrified (6)
I believe the answer is:
aghast
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">horrified</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 aghast that I've seen before include "Horror-struck" , "in awe" , "Filled with terror" , "Stupefied with horrer" , "Filled with horror or shock" .)