The crossword solution for the term 'very challenging' is the word 'HARD'. This word is often used to describe a task or situation that requires a lot of effort and dedication to complete. It can also refer to something that is difficult to understand or comprehend. HARD work is usually necessary in order to achieve success in any endeavor. The term 'very challenging' implies that the task or situation is especially difficult and requires a great deal of effort and dedication.