What does the cryptic crossword clue "Deer overturned cask leaking contents (4)" mean?

The definition is "Deer". The wordplay uses a hidden word. Hidden reversed in "deer overturned caSK LEaking contents" The answer is ELKS.

Deer overturned cask leaking contents (4)

Guardian Cryptic #29366 | 29 Down | 2024-04-25 flower