Complex sentence: Nagarjuna has crooned a special song in this film with his own voice after 17 years previously he "sing a song" in movie "Seetharama Raju" (1999).
Split into simpler sentences: Nagarjuna has crooned a special song in this film with his own voice after 17 years. He previously sang for the movie "Seetharama Raju" (1999).