The sole legitimate purpose of having a retired intelligence operative retain a clearance is so they can be a consultant to the current administration.
When Brennan made wild accusations of treason, he negated any reason he should retain his clearance, as obviously that administration is not going to seek his assistance.
And yes, an intelligence officer should at least know the definition of treason.
And this wild card nut, along with the perjuring Clapper, are the beginnings of the Mueller investigation.
That’s what’s scary.
Its very unusual for a former Intel chief like Brennan, Clapper etc to be that often on TV, taking part at that hounding. Their behaviour is the evidence they act against America and American interests