Possible Clues:

• Nerve fiber
• To cancel Mass, say, at end of day is a bit of a nerve
• Branch of thieves' organisation tried reforming
• Crystal read finally — aim with special procedure
• Treelike mark on a stone
• Crystalline tree-like structure
• A mineral crystallised in the shape of a tree
• Awfully tired after retreat, with 14-like extension to nerve cell
• I'd rented new extension to cell
• Dried net of the nerve fibre