Without warning, unexpectedly (8)
I believe the answer is:
suddenly
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">without warning</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">unexpectedly</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for suddenly that I've seen before include "Happening without warning" , "Quickly, unexpectedly" , "Out of the blue" , "Quickly and without warning" , "In an unexpected manner" .)