user: Question: Which championship has Roger Federer as an opponent on a Clay surface in a year earlier than 2007?
Columns: ['Outcome', 'Year', 'Championship', 'Surface', 'Opponent', 'Score']
Types: ['text', 'real', 'text', 'text', 'text', 'text']
Sample row: ['Winner', 2005.0, 'French Open (1)', 'Clay', 'Mariano Puerta', '6–7 (6–8) , 6–3, 6–1, 7–5']
SQL:

assistant: SELECT "Championship" FROM "Table" WHERE "Opponent" = 'Roger Federer' AND "Surface" = 'Clay' AND "Year" < 2007.0;