Clue: Fruit, small and bad, in front of sign with assortment (7,6)
Answer: SEVILLE ORANGE
Explanation: Definition: Fruit
A charade of S ('small') plus EVIL ('bad') plus LEO ('sign' of the zodiac) plus RANGE ('assortment'), for the bitter orange which is the basis of any orange marmalade worthy of the name (actually I have had a passable marmalade made from calamondin oranges).