user: Question: What is the score in the final of the tournament with a Clay surface on 18 April 2011?
Columns: ['Outcome', 'Date', 'Tournament', 'Surface', 'Opponent in the final', 'Score in the final']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', '24 November 2008', "La Vall d'Uixó , Spain", 'Clay', 'Leticia Costas', '6–2, 6–1']
SQL:

assistant: SELECT "Score in the final" FROM "Table" WHERE "Surface" = 'Clay' AND "Date" = '18 April 2011';