Broadcast excellent by socialist (5)
I believe the answer is:
aired
'broadcast' is the definition.
(synonyms)
'excellent by socialist' is the wordplay.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'by' is a charade indicator (letters next to each other).
'socialist' becomes 'red' (red can informally mean a socialist).
'ai'+'red'='AIRED'
(Other definitions for aired that I've seen before include "Exposed for drying" , "Made public" , "Vented to or exposed to breeze" , "Exposed to breeze for freshening - say damp clothes" , "Broadcast; dried" .)