The most common and most likely answer to this crossword clue is the 5 letter word COYPU
I've seen this crossword clue in The Daily Telegraph
C
O
Y
P
U
More clues leading to the result COYPU
- Not letting cat out of bag, having lead around rodent
- Rodent initially caught on yellow plant, unfortunately
- Furry creature, evasive and revolting, from the south
- Animal is a shy bear, by the sound of it
- Reportedly, bashful bear that’s hunted for fur
- Large rodent, timid baby dropping tail
- Aquatic rodent is evasive with place cut off
- Rodent turning up, timid at first
- Rodent getting self-effacing cat half-cut
- Bashful and Happy rolled over rodent
Buddy explains!

The straight part
We know that "S American native" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case s american native = coypu.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 COYPU mean?
COYPU noun- A large, crepuscular, semiaquatic rodent (Myocastor coypus) resembling a large rat, having bright orange-yellow incisors, native to South America and introduced to Europe, Asia and North America, valued for its fur in eastern Europe and central Asia and considered a pest elsewhere.