Sanction, as broadcast (6)
I believe the answer is:
assent
'sanction' is the definition.
(I've seen this before)
'as broadcast' is the wordplay.
'broadcast' becomes 'sent' (sent or transmitted as a broadcast).
'as'+'sent'='ASSENT'
(Other definitions for assent that I've seen before include "Agreement or concurrence" , "Accede, acquiesce" , "Say yes" , "Permission" , "Agree and concur" .)