Main unit for broadcasters opening in Yale? (7)
I believe the answer is:
keyhole
'opening in yale?' is the definition.
(Yale is a type of lock)
'main unit for broadcasters' is the wordplay.
'main' becomes 'key'.
'unit' becomes 'whole' (a whole unit of something).
'for broadcasters' indicates a 'sounds like' (homophone) clue (how the word might sound over a broadcast).
'whole' sounds like 'hole'.
'key'+'hole'='KEYHOLE'
(Other definitions for keyhole that I've seen before include "Opening for the opener" , "Aperture in lock - kind of surgery" , "Aperture for lock opening" , "Type of surgery" , "Opening in door etc" .)