The term 'Upright Worker' can be solved by the crossword solution 'TUNER' (5 letters). A TUNER is a person who adjusts or repairs musical instruments, such as pianos, to ensure they are producing the correct sound. They use specialized tools and techniques to adjust the instrument's strings, keys, and other components to achieve the desired sound. Tuners must have a good ear for music and an understanding of how different instruments work in order to be successful.