The song to guess is : Lightning Strikes Twice
The 2 first clues indicates something that came two times, so twice. The 3rd clue is a movie from 1951. The 4th is about someone who's afraid and "sitting in a corner alone". The 5th clue is talking about "The Angel And The Gambler" and "The Clansman", two long songs between which "Lightning Strikes Twice" is sandwiched. And the 6th clue is about Nelson Mandela and his birthplace destroyed by lightning.