The crossword solution for the term 'Make a sinner thinner?' is 'LISP', which stands for 'Lose Inches Super Quickly'. LISP is a diet program that focuses on reducing inches from the waistline and other areas of the body. It is based on the idea that if you reduce your caloric intake and increase your physical activity, you can lose weight quickly and safely. The program also includes lifestyle changes such as eating healthier foods and getting more sleep.