Place chunks of onion and celery and 1/2 lemon in slow cooker.
Remove turkey breast from packaging, remove skin, then pat dry with paper towels. Place turkey breast in slow cooker on top of onions, celery, and lemon. Squeeze remaining lemon half over the turkey, then add lemon to slow cooker.
Rub olive oil on turkey breast. Combine seasonings and rub on turkey breast. Pour chicken broth and wine around turkey,
Cover and cook on low for 5 to 7 hours, or until a meat thermometer reads 165 degrees. Make sure the thermometer is not touching bone.
Remove from slow cooker and let it rest for 15 minutes before slicing.