Broadcasting organisation in King's Cross, say (7)
I believe the answer is:
station
I believe this clue is a double definition.
'broadcasting organisation' is the first definition.
'king's cross say' is the second definition.
(King's Cross is a London train station)
'in' acts as a link.
(Other definitions for station that I've seen before include "place to go to train" , "Waterloo perhaps" , "Such as Victoria" , "Building where service is based, fire or train" , "position in society?" .)