1. Preheat oven to 425°. Combine fennel, 1 teaspoon oil, salt, and pepper on a shallow baking sheet; roast, turning occasionally until golden on edges and tender (about 20 minutes).
2. While fennel is roasting, combine juice and next 5 ingredients (through cinnamon) in a small bowl, stirring well with a whisk. Add remaining 3 teaspoons oil, stirring well; set aside.
3. Place watercress, clementine or orange sections, radicchio, and roasted fennel in a large bowl. Add vinaigrette; toss well. Garnish with pomegranate seeds; serve immediately.