CREATE TABLE table_6643 ("Club" TEXT, "Played" TEXT, "Drawn" TEXT, "Lost" TEXT, "Points for" TEXT, "Points against" TEXT, "Tries for" TEXT, "Tries against" TEXT, "Try bonus" TEXT, "Losing bonus" TEXT, "Points" TEXT)

What did the loss come from a Club of mumbles rfc?
SELECT "Lost" FROM table_6643 WHERE "Club" = 'mumbles rfc'
SELECT "Lost" FROM "table_6643" WHERE "Club" = 'mumbles rfc'