Affright (5)
I believe the answer is:
alarm
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">affright</span>' is the definition.<br/ ><span class="explanation-format__explanation">(alarming is a kind of affrighting)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for alarm that I've seen before include "Fright" , "A rousing sound in the morning" , "It signals danger" , "Unnerve" , "Wake-up call?" .)