The BBC (4)
I believe the answer is:
beeb
'the bbc' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for beeb that I've seen before include "Informally, the British broadcasting service" , "BBC (colloq" , "Auntie (slang, palindrome)" , "BBC (informally)" , "BBC, familiarly" .)