CREATE TABLE table_18514 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

In the District Tennessee 7 what is the number of first elected?
SELECT MAX("First elected") FROM table_18514 WHERE "District" = 'Tennessee 7'
SELECT MAX("First elected") FROM "table_18514" WHERE "District" = 'Tennessee 7'