The most common and most likely answer to this crossword clue is the 4 letter word ANOA
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More clues leading to the result ANOA
Buddy explains!

The straight part
We know that "Wild beast" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wild beast = anoa.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 ANOA mean?
ANOA noun- Any of either Bubalus quarlesi or Bubalus depressicornis, being species of small Indonesian water buffalo similar in appearance to a deer.