kirky, the instructions are confusing.
For 23a, only one letter goes, since 4 of them are in Ref#1, Ref#2 and the song title.
The last column's 6 letter word, 5 go,M stays.
Third column's down clue 2 go.
4th row, 5 letters, 3 go.
Row 5: 9 letter word, 5 go.
If my interpretation is correct, that would be 16.