The most common and most likely answer to this crossword clue is the 5 letter word AZTEC
I've seen this crossword clue in The Daily Telegraph
A
Z
T
E
C
More clues leading to the result AZTEC
- A variable investigator, one of Mexican Indian extraction
- Old Mexican Indian, a variable investigator
- Old Mexican detective following two in centre of piazza
- American shiraz technician bottles
- Ancient civilization originally capturing unknown tribespeople for evisceration
- An old Mexicanâs extreme letters seen by sleuth
- Old person has a college reported in the East End
- Early American map followed by sleuth
- Bygone language investigator associated with extremists
- A note in Zulu about ancient person
Buddy explains!

The straight part
We know that "Early American" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case early american = aztec.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.