What dance was Leeza Gibbons the worst dancer for, receiving a score lower than 15?
CREATE TABLE "highest_and_lowest_scoring_performances" (
  "dance" text,
  "best_dancer" text,
  "best_score" real,
  "worst_dancer" text,
  "worst_score" real
);
SELECT MIN("best_score") FROM "highest_and_lowest_scoring_performances" WHERE "worst_dancer"='leeza gibbons' AND "worst_score"<15;