Drain pineapple, reserving all of the liquid in a 1-quart liquid measuring cup. Remove 1 Tbsp. of the crushed pineapple; set aside for garnish. Add enough cold water to the reserved liquid to measure 3 cups; pour into large saucepan. Bring to boil; remove from heat. Add gelatin; stir at least 2 minutes until completely dissolved. Add cranberry sauce; stir until well blended. (Note: Due to the presence of whole berries in the cranberry sauce, the gelatin mixture will not be smooth.) Pour into large bowl. Refrigerate 1 1/2 hours or until slightly thickened (consistency of unbeaten egg whites.)
Stir in remaining pineapple, apple, and walnuts; stir gently until well blended. Pour into medium serving bowl.
Refrigerate 4 hours or until firm. Garnish with reserved crushed pineapple just before serving. Store leftover gelatin in refrigerator.