Retreat observed in the BBC (3)
I believe the answer is:
ebb
'retreat' is the definition.
(ebb can mean to fall back or retreat)
'observed in the bbc' is the wordplay.
'observed in' indicates the answer is hidden within the clue.
'EBB' is hidden in the letters of 'the bbc'.
(Other definitions for ebb that I've seen before include "Withdraw heartless" , "Initially Mrs Browning's" , "recession" , "Tidal outflow" , "Not to wax" .)