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Film of oil on water (5)

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

• Quick crossword No 16,078 — 2021-11-17 00:00:21
  4D: Superficially impressive (5)
• Quick crossword No 15,992 — 2021-08-08 23:00:34
  13A: Film of oil on water (5)