The most common and most likely answer to this crossword clue is the 5 letter word FOYER
F
O
Y
E
R
More clues leading to the result FOYER
Buddy explains!

The straight part
We know that "anteroom" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case anteroom = foyer.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 FOYER mean?
FOYER noun- A lobby, corridor, or waiting room, used in a hotel, theater, etc.
- The crucible or basin in a furnace which receives the molten metal.
- A hostel offering accommodation and work opportunities to homeless young people.