Grave danger (5)
I believe the answer is:
peril
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grave danger</span>' is the definition.<br/ ><span class="explanation-format__explanation">(peril means great danger)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for peril that I've seen before include "Danger, jeopardy" , "Danger, hazard" , "Quest" , "risk" , "Hazardous situation" .)