Meddling, confusing virtue with sin (9)
I believe the answer is:
intrusive
'meddling' is the definition.
(similar in meaning)
'confusing virtue with sin' is the wordplay.
'confusing' indicates an anagram.
'with' means one lot of letters go next to another.
'virtue' after 'sin' is 'sinvirtue'.
'sinvirtue' anagrammed gives 'INTRUSIVE'.
(Other definitions for intrusive that I've seen before include "Presumptuous" , "Meddlesome" , "disturbing" , "Tending to enter uninvited" , "Being present uninvited" .)