The most common and most likely answer to this crossword clue is the 4 letter word HARE
I've seen this crossword clue in The Sunday Telegraph
H
A
R
E
More clues leading to the result HARE
- Fast runner — he holds a record at first
- Scatty, like a fast mover in form?
- Scots have to contain river that runs in field
- Almost all concubines hurry
- In conversation, shock fast runner
- Animal fur, allegedly
- One 16 stopping another in race
- One runs in haste, taking bounds
- Shock for commentator – runner coming into form
- Animal in shock, by the sound of it?
Buddy explains!

The straight part
We know that "Animal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case animal = hare.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 HARE mean?
HARE noun- Any of several plant-eating animals of the family Leporidae, especially of the genus Lepus, similar to a rabbit, but larger and with longer ears.
- The player in a paperchase, or hare and hounds game, who leaves a trail of paper to be followed.
- To move swiftly.
- To excite; to tease, or worry; to harry.
- Grey, hoary; grey-haired, venerable (of people).
- Cold, frosty (of weather).