Military trumpet (5)
I believe the answer is:
bugle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">military trumpet</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 bugle that I've seen before include "Military musical instrument" , "Brass instrument without valves" , "Small trumpet; plant" , "Trumpet-like instrument" , "A military trumpet" .)