user: Question: What circuit did Clay Regazzoni win?
Columns: ['Race Name', 'Circuit', 'Date', 'Winning driver', 'Constructor', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['XIV Argentine Grand Prix', 'Buenos Aires', '24 January', 'Chris Amon', 'Matra', 'Report']
SQL:

assistant: SELECT "Circuit" FROM "Table" WHERE "Winning driver" = 'Clay Regazzoni';