Remaining actors, dull (8)
I believe the answer is:
overcast
'dull' is the definition.
(as in dull weather)
'remaining actors' is the wordplay.
'remaining' becomes 'over' (as in 'we ate them all but had one over').
'actors' becomes 'cast' (group of actors).
'over'+'cast'='OVERCAST'
(Other definitions for overcast that I've seen before include "not entirely fair" , "Overacts, being gloomy" , "The sky covered by dark clouds" , "Gloomy like cloudy sky" , "State of the sky when it is covered by clouds" .)