Al Pacino apologized on Monday for his singing in the movie in which he plays the aging rock star Danny Collins. The 75-year-old Pacino delivers a rare comic turn in the film about a singer who discovers a letter written to him by John Lennon four decades earlier. At the London premiere of "Danny Collins" at the Ham Yard Hotel, he joked: "I am sorry about the singing but I have to do it in the part." The star of "The Godfather" and "Scarface" admitted he suffered from nerves when the script demanded he perform in front of a crowd. Pacino said, "I will tell you the one thing you learn about singing in front of an audience is it's really hard to hang onto the words."??