Act of deliberate betrayal (7)
I believe the answer is:
treason
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">act of deliberate betrayal</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for treason that I've seen before include "Betrayal (of one's country)" , "Perfidy" , "Lese-majesty" , "One rats (anag)" , "Disloyalty (to one's country)" .)