1. If someone beats another person to within an inch of their life, they beat them very severely. His fists were clenched as if he were going to beat Smythe to within an inch of his life.

2. You can use to within an inch of their life or within an inch of their life after a verb to say that someone does something to an extreme degree. Can a classic car that has been restored to within an inch of its life still be described as original? You can see them shopping in London stores, groomed within an inch of their lives, with their best sides ready for any passing press photographer.