Sudden uncontrollable fear (5)
I believe the answer is:
panic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sudden uncontrollable fear</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 panic that I've seen before include "Fear out of sixteen ac" , "Greek god" , "Sudden alarm" , "Sudden extreme anxiety" , "Sudden overpowering anxiety" .)