Unmanned aerial vehicle (5)
I believe the answer is:
drone
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unmanned aerial vehicle</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 drone that I've seen before include "Bee, speak tediously" , "Idle type" , "Talk boringly; a parasite" , "Sustained bass note accompanying a melody - male bee" , "He buzzes, but not with energy!" .)