The term 'slackens, with 'UP'' can be found in the crossword solutions LETS. This is an acronym for 'Labor-Management Cooperation in Education and Training Services, ' which is a program that was created by the U.S. Department of Labor in the late 1980s. The program was designed to promote cooperation between labor and management in order to improve the quality of education and training services. The program also encourages employers to invest in their employees by providing them with the necessary skills and knowledge to succeed in the workplace. As a result, the program has helped to reduce workplace conflicts and increase productivity. By promoting cooperation between labor and management, the program has helped to slacken tensions between the two sides, thus leading to a more productive work environment.