Accomplished players seen as dull (8)
I believe the answer is:
overcast
'dull' is the definition.
(as in dull weather)
'accomplished players' is the wordplay.
'accomplished' becomes 'over' (I've seen this before).
'players' becomes 'cast' (group of actors).
'over'+'cast'='OVERCAST'
'seen as' acts as a link.
(Other definitions for overcast that I've seen before include "Gloomy like cloudy sky" , "less than fine" , "Overacts, being gloomy" , "Cloud-covered" , "(Of skies) grey" .)