The most common and most likely answer to this crossword clue is the 4 letter word NEVI
N
E
V
I
Buddy explains!
The straight part
We know that "American spots" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case american spots = nevi.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 NEVI mean?
NEVI noun- Any of a number of different, usually benign, pigmented, raised or otherwise abnormal lesions of the skin.