Gloomy about actors (8)
I believe the answer is:
overcast
'gloomy' is the definition.
(I've seen this before)
'about actors' is the wordplay.
'about' becomes 'over' (both can mean around).
'actors' becomes 'cast' (group of actors).
'over'+'cast'='OVERCAST'
(Other definitions for overcast that I've seen before include "Overacts, being gloomy" , "not entirely fair" , "State of the sky when it is covered by clouds" , "Sunless" , "Gloomy like cloudy sky" .)