Relatives in BBC succeeded (7)
I believe the answer is:
aunties
'relatives' is the definition.
(auntie is a kind of relative)
'bbc succeeded' is the wordplay.
'bbc' becomes 'auntie' (nickname for the BBC).
'succeeded' becomes 's' (genealogical abbreviation).
'auntie'+'s'='AUNTIES'
'in' is the link.
(Other definitions for aunties that I've seen before include "family members" , "Female relations" , "Older female friends" , "Female relatives" , "Parent's sisters (informal)" .)