Long slog is a term used to describe a long and difficult journey. It is often used to refer to a journey that requires a lot of physical and mental effort. The term can also be used to describe a difficult task or project that requires a lot of time and effort to complete. In this crossword, the solution for the term 'long slog' is 'treks', which refers to a long journey or expedition. Treks are usually undertaken over a long period of time and involve travelling through difficult terrain.