Naughty Uncle Rod's a rogue (9)
I believe the answer is:
scoundrel
'a rogue' is the definition.
(thesaurus)
'naughty uncle rod's' is the wordplay.
'naughty' indicates anagramming the letters.
'uncle'+'rods'='unclerods'
'unclerods' is an anagram of 'SCOUNDREL'.
(Other definitions for scoundrel that I've seen before include "bad egg" , "Untrustworthy figure" , "Person that's low" , "Rascal" , "Disreputable type" .)