King penguin? (7)
I believe the answer is:
emperor
I believe this clue is a double definition.
'king' is the first definition.
(I've seen this before)
'penguin?' is the second definition.
(emperor penguin is a kind of penguin)
(Other definitions for emperor that I've seen before include "Ruler - penguin - size of paper" , "Say, Nero" , "Sovereign - ruler" , "Penguin of largest known species - a great ruler" , "chap such as Charlemagne" .)