Unmanned aerial vehicle (5)
I believe the answer is:
drone
'unmanned aerial vehicle' is the definition.
(I've seen this before)
This is the entire clue.
(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!" .)