The most common and most likely answer to this crossword clue is the 6 letter word GARRET
I've seen this crossword clue in The Times
G
A
R
R
E
T
More clues leading to the result GARRET
Buddy explains!
The straight part
We know that "room at the top" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case room at the top = garret.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 GARRET mean?
GARRET noun- An attic or semi-finished room just beneath the roof of a house.