Monotreme (7)
I believe the answer is:
echidna
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">monotreme</span>' is the definition.<br/ ><span class="explanation-format__explanation">(echidna is a kind of monotreme)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for echidna that I've seen before include "This insectivore" , "Toothless type" , "Little animal" , "Prickly creature" , "Insectivorous mammal" .)