Complex sentence: She was not assigned to the 2013 European Championships because Nikol Gosviani placed ahead of Leonova amongst the age-eligible ladies but she was sent to the 2013 World Championships.
Split into simpler sentences: She was not assigned to the 2013 European Championships because Nikol Gosviani placed ahead of Leonova amongst the age-eligible ladies. Leonova was sent to the 2013 World Championships.