This actor may be unconscious and read (10)
I believe the answer is:
understudy
'this actor' is the definition.
(understudy is a kind of actor)
'unconscious and read' is the wordplay.
'unconscious' becomes 'under' (as in under anaesthetic).
'and' is a charade indicator (letters next to each other).
'read' becomes 'study' ('study' can be a synonym of 'read').
'under'+'study'='UNDERSTUDY'
'may be' acts as a link.
(Other definitions for understudy that I've seen before include "one's hoping to get on" , "emergency role" , "One prepared to take over from leading actor" , "reserve?" , "Stage stand-in" .)