The most common and most likely answer to this crossword clue is the 9 letter word LOGORRHEA
I've seen this crossword clue in The Times
L
O
G
O
R
R
H
E
A
Buddy explains!

The straight part
We know that "problem for rambler in US?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case problem for rambler in us? = logorrhea.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 LOGORRHEA mean?
LOGORRHEA noun- Excessive talkativeness.
- Excessive use of words in writing; prolixity.
- Excessive and often uncontrollable speaking due to a mental disorder.