Setter not being edited is extremely bad (9)
I believe the answer is:
rottenest
'extremely bad' is the definition.
(bad can mean rotten or gone off)
'setter not being edited' is the wordplay.
'being edited' is an anagram indicator.
'setter'+'not'='setternot'
'setternot' anagrammed gives 'ROTTENEST'.
'is' is the link.
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