Unplanned broadcast of Peanuts soon? (11)
I believe the answer is:
spontaneous
'unplanned' is the definition.
(thesaurus)
'broadcast of peanuts soon?' is the wordplay.
'broadcast of' indicates anagramming the letters (I've seen 'broadcast' mean this (letters scattered or cast around)).
'peanuts'+'soon'='peanutssoon'
'peanutssoon' anagrammed gives 'SPONTANEOUS'.
(Other definitions for spontaneous that I've seen before include "Unprompted" , "Cause of Mr Krook's death" , "Impulsive, unpremeditated" , "Impromptu" .)