Downgrade pound after each broadcast (7)
I believe the answer is:
cheapen
'downgrade' is the definition.
(thesaurus)
'pound after each broadcast' is the wordplay.
'pound' becomes 'pen' (I've seen this before).
'after' says to put letters next to each other.
'broadcast' indicates an anagram.
'each' with letters rearranged gives 'chea'.
'pen' put after 'chea' is 'CHEAPEN'.
(Other definitions for cheapen that I've seen before include "lower" , "decrease in value" , "Depreciate" , "Tried" , "Reduce worth, degrade" .)