Villain's doctor welcomed by new counsel (9)
I believe the answer is:
scoundrel
'villain's' is the definition.
('scoundrel' can be a synonym of 'villain')
'doctor welcomed by new counsel' is the wordplay.
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'welcomed by' is an insertion indicator (I've seen this in other clues).
'new' is an anagram indicator.
'counsel' is an anagram of 'scounel'.
'dr' placed inside 'scounel' is 'SCOUNDREL'.
(Other definitions for scoundrel that I've seen before include "Unprincipled rogue" , "Hound" , "Untrustworthy figure" , "Rat" , "bad egg" .)