Ancient overseer refined sugar (5)
I believe the answer is:
argus
'ancient overseer' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'refined sugar' is the wordplay.
'refined' indicates anagramming the letters.
'sugar' with letters rearranged gives 'ARGUS'.
Can you help me to learn more?
(Other definitions for argus that I've seen before include "Many-eyed mythical monster" , "Small butterfly" , "Pheasant, butterfly, a hundred-eyed monster" , "Various brown butterflies" , "Hundred-eyed giant in mythology" .)