Looking down on sixteen characters (4)
I believe the answer is:
atop
'looking down on' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for atop that I've seen before include "Upon" , "in dominant position" , "At the apex" , "On a high" , "At the summit of" .)