The most common and most likely answer to this crossword clue is the 8 letter word SLUMLORD
I've seen this crossword clue in Financial Times
S
L
U
M
L
O
R
D
Buddy explains!
The straight part
We know that "A letter from across the tracks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a letter from across the tracks = slumlord.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 SLUMLORD mean?
SLUMLORD noun- A person who makes money by renting housing that is kept in poor condition.