Naval commander (7)
I believe the answer is:
admiral
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">naval commander</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for admiral that I've seen before include "Highest ranking naval officer" , "Powerful sailor" , "Red butterfly in charge of the fleet" , "Brightly coloured butterfly" , "Navy bigwig" .)