The most common and most likely answer to this crossword clue is the 7 letter word MARTENS
I've seen this crossword clue in The Daily Telegraph
M
A
R
T
E
N
S
More clues leading to the result MARTENS
Buddy explains!

The straight part
We know that "animals" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case animals = martens.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 MARTENS mean?
MARTENS noun- Any carnivorous mammal of the genus Martes in the family Mustelidae.
- Any of various passerine birds of the family Hirundinidae, which also includes swallows, that catch insects whilst flying.
- A perforated stone-faced runner for grinding.