Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_36 (championship VARCHAR, year VARCHAR, opponent VARCHAR, surface VARCHAR)
### Question:
Which championship has Roger Federer as an opponent on a clay surface in a year earlier than 2007?
### Answer:
SELECT championship FROM table_name_36 WHERE opponent = "roger federer" AND surface = "clay" AND year < 2007