Solemn (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">solemn</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for serious that I've seen before include "Solemn, thoughtful" , "Earnest; vital" , "Important - solemn" , "Earnest - important" , "Stern" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">solemn</span>' is the definition.<br/ ><span class="explanation-format__explanation">(grave can mean solemn or serious)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for grave that I've seen before include "Last resting place" , "In which to lay a corpse" , "Sleek, black" , "Solemn; tomb" , "Dignified" .)