Become extinct (3,3)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">become extinct</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 die out that I've seen before include "Expire completely, pass from existence" , "vanish" , "Expire gradually - perhaps a race or tribe" , "Disappear" , "Fade one after the other" .)