Luminary's current disadvantage (4)
I believe the answer is:
icon
'luminary's' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'current disadvantage' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'disadvantage' becomes 'con' (as in pros and cons).
'i'+'con'='ICON'
Can you help me to learn more?
(Other definitions for icon that I've seen before include "Something on computer screen" , "Something revered" , "Sprites" , "Admired figure" , "Representative symbol, may be on computer screen" .)