The most common and most likely answer to this crossword clue is the 8 letter word LALLYGAG
I've seen this crossword clue in The Guardian
L
A
L
L
Y
G
A
G
More clues leading to the result LALLYGAG
Buddy explains!

The straight part
We know that "Idle American" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case idle american = lallygag.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 LALLYGAG mean?
LALLYGAG noun- Horseplay, fooling around.
- A layabout, one who lallygags.
- (See lollygag.) To dawdle; to be lazy or idle; to avoid necessary work or effort.
- To pet, kiss, or otherwise demonstrate overt affection, generally in public.