PEAT

Partially carbonised vegetable matter saturated with water (4)

Solution has appeared in 2 crosswords (2 across and 0 down):

• Quick crossword No 15,835 — 2021-02-06 00:00:26
  19A: Traditional fuel from a bog (4)
• Quick crossword No 15,533 — 2020-02-19 00:00:40
  11A: Partially carbonised vegetable matter saturated with water (4)