Herald in confusion, turning green (9)
I believe the answer is:
messenger
'herald' is the definition.
(thesaurus)
'confusion turning green' is the wordplay.
'confusion' becomes 'mess' (mess can mean confusion or chaos).
'turning' is an anagram indicator.
'green' anagrammed gives 'enger'.
'mess'+'enger'='MESSENGER'
'in' acts as a link.
(Other definitions for messenger that I've seen before include "He brings the news - don't shoot him" , "One who bears a communication" , "Kind of bearer - don't shoot him" , "Emissary, courier" , "The role of Hermes or Mercury?" .)