Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_28209 ( "Celebrity" text, "Known for" text, "Age" real, "Professional" text, "Series" real, "Place" text, "Dances" real, "Highest score" real, "Lowest score" real, "Aggregate" real, "Average" text )

### Question ###
What was the aggregate for the celebrity who was known for being a singer and had 7 dances?

### Accurate SQL ###

SELECT "Aggregate" FROM table_28209 WHERE "Dances" = '7' AND "Known for" = 'Singer'