Junior naval officer (6)
I believe the answer is:
ensign
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">junior naval officer</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 ensign that I've seen before include "that's flown" , "Flag; standard-bearer" , "Ship's flag and junior officer" , "Soldier who carries the Colours" , "Flag; rank" .)