This is why broadcast is contrary to religious belief (6)
I believe the answer is:
heresy
'belief' is the definition.
(I have seen 'Unorthodox belief ' mean 'heresy' so perhaps 'belief' could also mean 'heresy')
'this is why broadcast' is the wordplay.
'this is' becomes 'here's' (both can be used to point out someone or something).
'broadcast' shows a homophone (sound like) (how the word might sound on the radio or TV).
'why' sounds like 'y'.
'heres'+'y'='HERESY'
'is contrary to religious' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for heresy that I've seen before include "not in good faith" , "The wrong idea" , "Unorthodox view" , "religious belief not generally accepted" , "Doctrine at variance with the orthodox position" .)