RN uniform colour (4,4)
I believe the answer is:
navy blue
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rn uniform colour</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 navy blue that I've seen before include "Colour darker than royal" , "Senior Service colour" , "Dark colour as worn by officers at sea" , "Armed service shade?" , "RN uniform colour" .)