Prattle from Big Herb is translated (9)
I believe the answer is:
gibberish
'prattle' is the definition.
(thesaurus)
'big herb is translated' is the wordplay.
'translated' indicates anagramming the letters.
'big'+'herb'+'is'='bigherbis'
'bigherbis' is an anagram of 'GIBBERISH'.
'from' is the link.
(Other definitions for gibberish that I've seen before include "Unintelligible talk, nonsense" , "Meaningless speech" , "Meaningless talk" , "Tosh" , "Rubbish" .)