A piece of fabric cut to completely cover a crack or break in a nail is a:

A piece of fabric cut to completely cover a crack or break in a nail is referred to as a repair patch. This tool is specifically designed to provide support and protection to the damaged area, allowing the nail to be reinforced and preventing further damage. The fabric used for repair patches is typically strong and adhesive, ensuring that it adheres well to the natural nail and remains in place.

Using a repair patch is a common technique in nail care, particularly when addressing issues such as splits, cracks, or breaks that can compromise the integrity of a nail. It allows the technician to mend the nail effectively while maintaining a natural appearance.

In contrast, other terms listed do not accurately describe this function. A wrap replacement refers to replacing the entire nail wrap rather than just addressing a localized problem, a stress strip is a smaller piece typically used for reinforcement of a specific area, and nail enhancement encompasses various procedures to improve or modify the overall appearance of the nail, not specifically focused on repairing damage.