Treachery or betrayal (7)
I believe the answer is:
treason
I believe this clue is a double definition.
'treachery' is the first definition.
(I know that treachery can be written as treason)
'betrayal' is the second definition.
(I know that betrayal can be written as treason)
(Other definitions for treason that I've seen before include "Offence against state" , "Criminal attempt to overthrow a government" , "Crime agains one's country" , "Senator (anag)" , "Mutiny" .)