Betrayal (7)
There are a few possibilities for this:
treachery
'betrayal' is the definition.
(synonyms)
This is all the clue.
(Other definitions for treason that I've seen before include "Crime agains one's country" , "Crime of national betrayal" , "LEse-majestE" , "Mutiny" , "Perfidy" .)
(Another definition for sellout that I've seen is " Commercial success - total betrayal".)
'betrayal' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for treachery that I've seen before include "Two-timing" , "Treason" , "Double-dealing" , "Deceptiveness" , "lack of loyalty" .)