I do. She must take a stand on this with the turmoil over the mountain and the thought that she showed weakness. Azgeda and the Ice Queen are bigger threats than your people, and I do not think she will risk breaking the alliance.
She weighs the pros and cons of this and has already made her mind up by asking you to be the thirteenth clan. If she does not follow through, or if it is another trick, she puts herself at risk of losing more support from the clans. It is most important for her to regain her strength, and betraying Clarke is less a move of strength than defeating back Azgeda for their advances.