CREATE TABLE table_name_99 (date VARCHAR, surface VARCHAR, result VARCHAR)

what is the date when the surface is clay and the result is 6 7 (4 7) , 1 6?
SELECT date FROM table_name_99 WHERE surface = "clay" AND result = "6–7 (4–7) , 1–6"
SELECT "date" FROM "table_name_99" WHERE "6–7 (4–7) , 1–6" = "result" AND "clay" = "surface"