In an empire where women are forbidden to rule, sixteen-year-old Olesya defies the law by entering a tournament that will decide the future tsar, only to fall in love with her biggest rival.
I like to set up my loglines with the following critera: an interesting character with a passion, an incident that affects the character, a risky/difficult goal for the character, something/someone in the way of that goal, and a risk of disaster expressed in terms of the previously stated passion.
Interesting character: Olesya, who is interesting because she's bucking tradition and defying laws. You go girl!
Incident: Hmmm the tournament? But what prompts her to enter the tournament is probably the "incident."
Risk/difficult goal: Winning a tournament against the odds.
Something/someone in the way: Her rival, but specifically, falling in love with her rival.
Risk of disaster: Losing the tournament? I don't really see much of a disaster here, actually, unless she's hopelessly in love with her rival and s/he still wants to kill her. That's a disaster for sure. But if the rival returns her feelings, then what would be the worst thing that would happen if she lost the tournament? Her rival would win, they'd hook up and be in love, badda bing.
Another story with love and tournaments: A Knight's Tale with Heath Ledger as the knight. His character is similar to Olesya because they're both participating in a tournament illegally. The risk for him, is if someone finds out he's not noble, he'll be arrested and punished in the medieval fashion (painfully and probably with plague somewhere). There's a romantic subplot, but it's independent of the true plot's passion and disaster. If the romantic subplot got deleted, we'd still have meaningful conflict.
I think this logline could work, because it gives the reader a great insight into Olesya's character already, and sets up the conflict and antagonist. I don't know what genre this is (besides fiction), but since the disaster is love related, my assumption is that it's romance? If it's a romance, then you've got your stakes. If not, then I wonder what the stakes are if she fails to win the tournament, or if she's discovered participating.