Who was the winner in stage 7 with a general classification of Pavel Tonkov?
CREATE TABLE "classification_leadership_by_stage" (
  "stage" text,
  "winner" text,
  "general_classification" text,
  "points_classification" text,
  "mountains_classification" text,
  "intergiro_classification" text,
  "trofeo_fast_team" text
);
SELECT "winner" FROM "classification_leadership_by_stage" WHERE "general_classification"='pavel tonkov' AND "stage"='7';