Who was the partner on the game which took place on a clay surface with opponents of marco chiudinelli michael lammer and a runner-up result?
CREATE TABLE "doubles_23_11_12" (
  "outcome" text,
  "date" text,
  "surface" text,
  "partner" text,
  "opponents" text,
  "score" text
);
SELECT "partner" FROM "doubles_23_11_12" WHERE "outcome"='runner-up' AND "surface"='clay' AND "opponents"='marco chiudinelli michael lammer';