___ penguin (7)
I believe the answer is:
emperor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">penguin</span>' is the definition.<br/ ><span class="explanation-format__explanation">(emperor penguin is a kind of penguin)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for emperor that I've seen before include "Beethoven piano concerto, Op. 73" , "Penguin of largest known species - a great ruler" , "Large richly coloured butterfly" , "A moth; a penguin" , "He rules over several states" .)