Trim excess fat from beef; pierce meat all over with a fork; place in a large glass bowl. Sprinkle with onion, salt, pepper, cloves. Add bay leaf and wine to bowl. Refrigerate, turning meat several times, overnight to marinate.

When ready to cook meat, remove from marinade; pat dry with paper towels. Brown in a large skillet. Place beef in slow cooker, stir in marinade, plus celery, garlic and onion soup, cover. Cook on Low for 10 hours or on High for 6 hours, or until beef is tender when pierced with a fork.

Remove beef to a heated platter and keep warm. Turn heat control to High. Combine flour and quarter cup cold water in a cup, stir into liquid in slow cooker until well-blended; cover; simmer 15 minutes.

Carve part of the roast into 1 cm thick slices. Arrange slices with rest of roast and Braised leeks on a large serving platter. Add parsley potatoes and steamed whole carrots, if you wish. Serve gravy separately to spoon over all.

BRAISED leeks: Trim roots and about half of the green tops from 1 bunch of leeks. Split each leek lengthwise; wash well. Arrange pieces, cut side down in a large skillet. Add just enough water to cover. Bring to boil, cover. Simmer 5 minutes, drain, return to pan. Add 3 tablespoons butter and sprinkle with half teaspoon salt and celery salt. Cook slowly 5 minutes longer or until leeks are tender. Green onions can be substituted for the leeks, use 2 bunches sliced in 8 cm pieces and cook a total of 6 minutes.