Editor picked up girl's broadcast (7)
I believe the answer is:
declare
'broadcast' is the definition.
(thesaurus)
'editor picked up girl's' is the wordplay.
'editor' becomes 'ed'.
'picked up' says the letters should be written backwards.
'girl' becomes 'clare' (**).
'ed' backwards is 'de'.
'de'+'clare'='DECLARE'
(Other definitions for declare that I've seen before include "say" , "State clearly, announce officially" , "Announce formally" , "Make clearly known" , "Make a statement, to customs perhaps" .)