The most common and most likely answer to this crossword clue is the 4 letter word EYAS
I've seen this crossword clue in The Guardian
E
Y
A
S
More clues leading to the result EYAS
- Young hawk and first eaglet, for example, soaring
- Very young hawk, unconstrained, tail up
- Old-fashioned musket, a feature of Plassey assuredly
- Unfledged bird always reared in centre of nest
- Hawk always returns south
- Hawk for example circling round by far edge of lake
- Young bird, for instance, soaring to east
Buddy explains!

The straight part
We know that "Young hawk" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case young hawk = eyas.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 EYAS mean?
EYAS noun- A young hawk or falcon in the nest, or that has not yet fledged, especially one that will be trained for falconry.