The most common and most likely answer to this crossword clue is the 3 letter word BOA
I've seen this crossword clue in The Daily Telegraph
B
O
A
More clues leading to the result BOA
- Pig runs away, seeing snake
- Stole or got from South American city
- Graduate packing old feather scarf
- Sort of scarf for snake
- Old boy repulsed by a snake
- Stole pig that has no tail
- Graduate packing old long feathery scarf
- Stole pig with rook making escape
- One having scaly body and feathers round neck
- Scarf got pinched from Latin American city
Buddy explains!

The straight part
We know that "snake" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case snake = boa.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 BOA mean?
BOA noun- Any of a group of large American snakes, of the genus Boa, subfamily Boinae, or family Boidae, including the boa constrictor, the emperor boa of Mexico, and the chevalier boa of Peru.
- (plural "boas") A type of scarf typically made from feathers.