Buzz finished when king enters (5)
I believe the answer is:
drone
'buzz' is the definition.
(I've seen this before)
'finished when king enters' is the wordplay.
I cannot really see how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is located in the answer.
'king' could be 'r' (abbreviation for rex, king in Latin) and 'r' is found in the answer.
The remaining letters 'de' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for drone that I've seen before include "small creature" , "Unmanned aerial vehicle" , "Continuous hum" , "Queen bee1s mate" , "Aircraft operated by remote control" .)