On what date did the match against Flavio Cipolla, played on a clay surface, occur?
CREATE TABLE "challengers_and_futures_17" (
  "date" text,
  "tournament" text,
  "surface" text,
  "opponent_in_the_final" text,
  "score" text
);
SELECT "date" FROM "challengers_and_futures_17" WHERE "surface"='clay' AND "opponent_in_the_final"='flavio cipolla';