Sudden terror (5)
(Other definitions for alarm that I've seen before include "Warning bell" , "It signals danger" , "Trepidation" , "Warning siren" , "Panicky arousal" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sudden terror</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for panic that I've seen before include "Losing one's head" , "Great consternation" , "Contagious fear" , "Frenzy" , "Grass" .)