The most common and most likely answer to this crossword clue is the 4 letter word HALL
I've seen this crossword clue in The Guardian
H
A
L
L
More clues leading to the result HALL
- Port city with area for university student residence
- Everyone at the back of hotel room
- Valhalla's large room
- Auditorium attracting English orchestra
- Shouts of acclaim much reduced for Manchester players
- Orchestra drops Elgar’s Introduction
- Challenge is too much for lobby
- Room for hire? Initially, everyone
- Intelligent computer left in dining room
- Hard on everybody in auditorium
Buddy explains!

The straight part
We know that "Room" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case room = hall.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 HALL mean?
HALL noun- A corridor; a hallway.
- A meeting room.
- A manor house (originally because a magistrate's court was held in the hall of his mansion).
- A building providing student accommodation at a university.
- The principal room of a secular medieval building.
- Cleared passageway through a crowd, as for dancing.
- A place for special professional education, or for conferring professional degrees or licences.
- A living room.