Bogged stuff is a term used to describe organic material that has been preserved in waterlogged conditions, such as PEAT bogs. PEAT is a type of soil made up of partially decayed plant matter, which can be harvested and used as fuel or fertilizer. It is formed over thousands of years in wetlands, and is composed of dead plants, mosses, and other organic matter. The four-letter answer to the crossword clue is PEAT.