CREATE TABLE "calendar" (
  "round" text,
  "main_date" text,
  "number_of_fixtures" real,
  "clubs" text,
  "new_entries_this_round" text,
  "prize_money" text,
  "player_of_the_round" text
);

Question: what is the club in the sixth round proper
SQL: SELECT "clubs" FROM "calendar" WHERE "round"='Sixth round proper';