Broadcast not originally by Empress of Blandings? (4)
I believe the answer is:
sown
'broadcast' is the definition.
(I've seen this before)
'not originally by empress of blandings?' is the wordplay.
'originally' indicates taking the first letters.
'by' is a charade indicator (letters next to each other).
'empress of blandings?' becomes 'sow' (fictional pig in PG Wodehouse novels).
The initial letter of 'not' is 'n'.
'n' put after 'sow' is 'SOWN'.
(Other definitions for sown that I've seen before include "Broadcast" , "Placed in ground as seed" , "set out to grow" , "(Of seed) planted" , "(Of seeds) planted" .)