Disloyal person giving new trio art (7)
I believe the answer is:
traitor
'disloyal person' is the definition.
(I've seen this before)
'new trio art' is the wordplay.
'new' is an anagram indicator.
'trio'+'art'='trioart'
'trioart' is an anagram of 'TRAITOR'.
'giving' is the link.
(Other definitions for traitor that I've seen before include "Betrayer, deceiver" , "Unreliable figure" , "One committing treason" , "Not a good subject" , "Rat riot (anag.)" .)