Frances Hodgson Burnett kid-lit novel ... and a hint to 21-, 26- and 45-Across 15 letters

Crossword clues for Frances Hodgson Burnett kid-lit novel ... and a hint to 21-, 26- and 45-Across 15 letters:

THESECRETGARDEN: Frances Hodgson Burnett kid-lit novel ... and a hint to 21-, 26- and 45-Across