The most common and most likely answer to this crossword clue is the 5 letter word AVIAN
I've seen this crossword clue in The Times
A
V
I
A
N
More clues leading to the result AVIAN
- Like birds initially imported in a commercial vehicle
- Article that’s seized by bird
- Referring to bird from Scandinavia, nesting
- Bird from banks of Amazon to keep passing through
- A vehicle crossing island of birds
- A food item chopped for birds
- A commercial vehicle carries one of the birds
- Flier: a through train at last
- Like a tyrant? Roman emperor is this following October
- Six into articles about birds
Buddy explains!

The straight part
We know that "Flier" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flier = avian.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 AVIAN mean?
AVIAN noun- A bird.
- A bird-like or flying creature.
- (furry fandom) Someone who roleplays or describes themselves as being a bird or bird-like animal character with human characteristics.
- Characteristic of or pertaining to birds, or to bird-like or flying creatures.