SELECT MIN("Goals against") FROM table_52018 WHERE "Goal Difference" = '7' AND "Losses" > '13'
Name the least goals for goal difference of 7 and losses more than 13
CREATE TABLE table_52018 (
    "Position" real,
    "Club" text,
    "Played" real,
    "Points" text,
    "Wins" real,
    "Draws" real,
    "Losses" real,
    "Goals for" real,
    "Goals against" real,
    "Goal Difference" real
)