The most common and most likely answer to this crossword clue is the 6 letter word GENETS
I've seen this crossword clue in The Times
G
E
N
E
T
S
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The straight part
We know that "beasts" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case beasts = genets.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does GENETS mean?
GENETS noun- Any of several Old World nocturnal, carnivorous mammals, of the genus Genetta in the family Viverridae, most of which have a spotted coat and a long, ringed tail.
- The fur of this mammal, or any skin dressed in imitation of it.
- A group of genetically identical individuals (plants, fungi, bacteria etc.) that have grown in a given location, all originating from asexual reproduction of a single ancestor; a group of ramets.
- A small-sized, well-proportioned, Spanish horse; a jennet.