The term 'FIND A FUNCTION FOR' is a job description for someone who is looking to USE their skills in a specific way. This could be a programmer, a mathematician, or someone with a similar skill set. The three letters in the crossword solution are 'USE', which indicates that the person should be able to USE their skills to find a function for a given task. This could involve writing code, solving equations, or any other task that requires a specific set of skills.