The most common and most likely answer to this crossword clue is the 5 letter word POPPA
P
O
P
P
A
More clues leading to the result POPPA
Buddy explains!

The straight part
We know that "the old man in America" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the old man in america = poppa.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 POPPA mean?
POPPA noun- (sometimes childish) father, papa.