Surprise, astound (4)
I believe the answer is:
stun
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">surprise</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(stunning is a kind of surprising)</span><br/ ><br/ >'<span class="explanation-format__original">astound</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 stun that I've seen before include "Daze, scatter senses" , "Daze, render semi-conscious" , "Knock into a semi-conscious state" , "cause amazement" , "Astound; render senseless" .)