Eclipsed (6)
(Other definitions for outshone that I've seen before include "Dwarfed" , "Made better or brighter impression than" .)
'eclipsed' is the definition.
('overshadow' can be a synonym of 'eclipse')
This is the entire clue.
(Other definitions for overshadowed that I've seen before include "Outshone" , "Eclipsed" .)