The most common and most likely answer to this crossword clue is the 10 letter word DOWNSTAIRS
I've seen this crossword clue in The Guardian
D
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S
More clues leading to the result DOWNSTAIRS
- Detective about to have good look, reportedly, closer to cellar?
- Far from happy, famous person’s going round one part of building
- County’s crewmen bringing one in on the ground floor, perhaps
- This kind of clue, by the sound of it, looks on a lower level
- Not working, fusses about a lower level position
- Not up? But you may be up if you are here!
- Depressed, fusses about a place for servants
Buddy explains!

The straight part
We know that "on the ground floor, perhaps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case on the ground floor, perhaps = downstairs.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 DOWNSTAIRS mean?
DOWNSTAIRS noun- The lower floor of a house, at ground level.
- The genitalia
- A floor lower than the current one.
- Living, stepping, or coming down the stairs