What is the average round for Wisconsin when the overall is larger than 238 and there is a defensive end?
CREATE TABLE "nfl_draft" (
  "round" real,
  "overall" real,
  "player" text,
  "position" text,
  "school_club_team" text
);
SELECT AVG("round") FROM "nfl_draft" WHERE "overall">238 AND "position"='defensive end' AND "school_club_team"='wisconsin';