SCUM

Floating film of muck (4)

Solution has appeared in 2 crosswords (1 across and 1 down):

• Quick crossword No 16,694 — 2023-11-07 00:00:51
  16A: Floating muck (4)
• Quick crossword No 16,032 — 2021-09-23 23:00:01
  18D: Floating film of muck (4)