The most common and most likely answer to this crossword clue is the 5 letter word DINER
I've seen this crossword clue in Financial Times
D
I
N
E
R
More clues leading to the result DINER
- Restaurant‘s row about turnover
- Dollar is not exorbitant rate… for customers here?
- US restaurant some criticised in error
- Reagan’s first lady set up trendy American restaurant
- One keen to eat arrested in Erith stores
- One who eats his meal half-heartedly?
- One having meal in American restaurant
- One eats some food in error
- Half-hearted meal in small restaurant
- US soldier leaving less attractive US restaurant
Buddy explains!

The straight part
We know that "US restaurant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case us restaurant = diner.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 DINER mean?
DINER noun- One who dines.
- A dining car in a railroad train.
- A typically small restaurant, usually modeled after a railroad dining car, that serves lower-class fare, normally having a counter with stools along one side and booths on the other, and often decorated in 50s and 60s pop culture themes and playing popular music from those decades.