Second buzzer for auntie (4)
I believe the answer is:
beeb
This clue could be a double definition.
'second buzzer' is the first definition.
The definition suggests a singular noun which matches the answer.
'auntie' is the second definition.
(both are nicknames for the BBC)
'for' acts as a link.
(Other definitions for beeb that I've seen before include "Informally, the British broadcasting service" , "British Broadcasting Corporation (popularly)" , "BBC (colloq" , "It broadcasts" , "Old microcomputer" .)