Clue: One who scored piece of music found in front of unsigned library book (5,4)
Answer: BARRY JOHN
Explanation: One who scored piece of music found in front of unsigned library book (5,4)
All sorts of deviousness here. A charade of BAR ('piece of music' but not a complete one) plus RY ('[libra]ry' without LIBRA {'sign' of the zodiac}) plus JOHN ('book' of the New Testament). For once the 'one who scored' is not a composer, but the Welsh Rugby player – although swapping the two names gives JOHN BARRY, who was a composer, and appears as such in 6A, 25A, 17D and 1,9D.