Confusion spread by broadcast and stupidity (7)
I believe the answer is:
madness
'stupidity' is the definition.
(thesaurus)
'confusion spread by broadcast and' is the wordplay.
'confusion' becomes 'mess' (I've seen this before).
'spread by' is an insertion indicator (the word is spread open by inserted letters).
'broadcast' indicates anagramming the letters.
'and' is an anagram of 'adn'.
'mess' enclosing 'adn' is 'MADNESS'.
(Other definitions for madness that I've seen before include "Insanity" , "Lunacy - ska/pop band" , "Folly" , "Utter foolishness" , "hysteria?" .)