2 packages (1-3/4 ounces each) powdered fruit pectin
6 cups sugar
1/2 teaspoon ground cinnamon
1 cup chopped walnuts, toasted
In a Dutch oven over medium-high heat, bring apples, pears, clementines and lemon juice to a boil, stirring constantly. Reduce heat; simmer, uncovered, 10 minutes or until fruit is tender, stirring occasionally.
Stir in pectin. Bring to a full rolling boil over high heat, stirring constantly. Stir in sugar and cinnamon; return to bring to a full rolling boil. Boil and stir 1 minute.
Remove from heat; skim off foam. Stir in walnuts. Ladle hot mixture into eight hot half-pint jars, leaving 1/4-in. headspace. Remove air bubbles and adjust headspace, if necessary, by adding hot mixture. Wipe rims. Center lids on jars; screw on bands until fingertip tight.
Place jars into canner with simmering water, ensuring that they are completely covered with water. Bring to a boil; process 10 minutes. Remove jars and cool.