The term 'long slog' can be summarized as a long and difficult journey. The crossword solution for this term is 'TREK, ' which is defined as a long and arduous journey, usually involving walking. It is often used to describe a journey that is taken on foot, especially in areas with difficult terrain. Trekking is a popular activity among hikers and adventurers, as it allows them to explore remote areas and experience nature in its rawest form.