Extensive group of actors for show (9)
I believe the answer is:
broadcast
'show' is the definition.
(broadcast is a kind of show)
'extensive group of actors' is the wordplay.
'extensive' becomes 'broad' (similar in meaning).
'group of actors' becomes 'cast' (I've seen this in another clue).
'broad'+'cast'='BROADCAST'
'for' acts as a link.
(Other definitions for broadcast that I've seen before include "distributed by hand" , "Transmit (programme)" , "Send out over the airwaves" , "Send out by radio or television" , "Transmit over airwaves" .)