Go on and on in given order travelling north (5)
I believe the answer is:
Here is my best explanation:
'go on and on' is the definition.
'in given order travelling north' is the subsidiary indication.
'in' indicates a hidden word.
'travelling north' says the letters should be written in reverse (in a down clue, letters go up).
'enord' can be found hidden inside 'given order'.
'enord' written backwards gives 'drone'.
(Other definitions for drone that I've seen before include "he gives us a buzz", "Remote controlled aircraft", "Buzzing sound", "Talk boringly; male bee", "RPV", "Speak long and tediously", "Monotone", "Aeroplane", "Male honey bee, an idler" and "Male honeybee".)