Possible Clues:

• Catholic string
• Religious aid on which one can count
• It’s prayed upon
• Prayer beads, for some
• Beads twisted or perhaps about right
• A sorry criminal picked up in the church when saying prayers
• 'The Secret of the --', book by St Louis de Montfort
• Promising to hold retreat, initially after a series of prayers
• Catholic devotion
• Aid to prayer