The most common and most likely answer to this crossword clue is the 5 letter word MAYAN
M
A
Y
A
N
More clues leading to the result MAYAN
- One of the old people with a refusal in the morning to get up
- A Yankee probing fellow of a bygone civilisation
- Old Mexican’s refusal in the morning to get up
- Primarily, Mesoamerican / ancient Yucatan, architecturally notable?
- South American article appears after a month
- Old American‘s vote not to put up dam to the north
- Month needed to cover a new Indian language
- American native’s origins after might of ancient race
- Edible tuber returned by an ancient South American
- Month with an inhabitant of Yucatan
Buddy explains!

The straight part
We know that "ancient South American" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ancient south american = mayan.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.