1. In a large mixing bowl, whisk together the arak, olive oil, orange juice, lemon juice, mustard, brown sugar, salt and pepper. Set aside.
2. Trim the fennel and cut each bulb in half lengthwise. Cut each half into 4 wedges.
3. Add the fennel to the bowl with the liquids, along with the chicken pieces, clementine slices, thyme and fennel seeds. Stir well with your hands, then cover the bowl and let the mixture marinate in the fridge for a few hours or overnight (if you are pressed for time, skipping the marinating stage is fine).
4. Preheat the oven to 475°F. Transfer the chicken and its marinade to a large baking sheet, and spread all the pieces out in a single layer; the chicken skin should be facing up. Transfer the baking sheet to the oven and roast for 35 to 45 minutes, until the chicken is browned and cooked through. Remove from the oven.
5. Using a spatula, transfer the chicken, fennel, and clementines to a serving platter; cover with foil to keep warm.
6. Pour the cooking liquid into a small saucepan and set it over medium-high heat. Bring the liquid to a boil, reduce the heat to low and simmer until the sauce is reduced by one-third, so you are left with about 1 cup.
7. Pour the hot sauce over the chicken, garnish with chopped fresh parsley, and serve.