Organise a selection to be broadcast (7)
I believe the answer is:
arrange
'organise' is the definition.
(arranging is a kind of organizing)
'a selection to be broadcast' is the wordplay.
'selection' becomes 'range' (a selection is a range of things).
'to be broadcast' indicates a 'sounds like' (homophone) clue (I've seen 'being broadcast' mean this).
'range' is a homophone of 'rrange'.
'a'+'rrange'='ARRANGE'
(Other definitions for arrange that I've seen before include "Put in order - organise" , "Rare nag (anag.)" , "Put in order; make plans" , "Order, plan or design" , "Organise, plan" .)