The most common and most likely answer to this crossword clue is the 6 letter word AVIARY
I've seen this crossword clue in The Times
A
V
I
A
R
Y
More clues leading to the result AVIARY
- Mass of eggs, but not the first year in bird sanctuary
- Area by railway where air travel the norm?
- A change involving one home for birds
- A change involving island enclosure for birds
- Where birds may be accessed at first, using public transport?
- Group in circulation taking train where air travel the norm
- Birds' enclosure originally accessed by means of railway
- A line crossing Italian street’s home to birds
- Where one might see high flyers having some caviar? Yes!
- A seesaw covering middle of big bird cage
Buddy explains!

The straight part
We know that "Where birds may be" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case where birds may be = aviary.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 AVIARY mean?
AVIARY noun- A house, enclosure, large cage, or other place for keeping birds confined; a birdhouse.