The very same dialect in broadcast (9)
I believe the answer is:
identical
'the very same' is the definition.
(I've seen this before)
'dialect in broadcast' is the wordplay.
'broadcast' indicates anagramming the letters.
'dialect'+'in'='dialectin'
'dialectin' with letters rearranged gives 'IDENTICAL'.
(Other definitions for identical that I've seen before include "as B and B" , "Equal" , "lacking distinction" , "Aid client to be the very same" , "Selfsame" .)