Last stage of insect development (5)
I believe the answer is:
imago
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">last stage of insect development</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for imago that I've seen before include "being immature?" , "Winged insect -- amigo (anag)" , "Last stage of insect's development" , "Beetle, for example" , "Adult insect after metamorphosis" .)