user: Question: Who was the winning driver of the race with Clay Regazzoni as the fastest lap and Jackie Stewart as the pole position?
Columns: ['Race', 'Circuit', 'Date', 'Pole position', 'Fastest lap', 'Winning driver', 'Constructor', 'Tyre', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['South African Grand Prix', 'Kyalami', '7 March', 'Jackie Stewart', 'Jack Brabham John Surtees', 'Jack Brabham', 'Brabham - Ford', 'G', 'Report']
SQL:

assistant: SELECT "Winning driver" FROM "Table" WHERE "Fastest lap" = 'Clay Regazzoni' AND "Pole position" = 'Jackie Stewart';