The most common and most likely answer to this crossword clue is the 9 letter word ATTENDANT
I've seen this crossword clue in The Guardian
A
T
T
E
N
D
A
N
T
More clues leading to the result ATTENDANT
- Usher in National Theatre following a dry finale with a bit of applause
- A dry conclusion by a property owner’s valet
- Related to waiter
- Escort coming in at 10
- Waiter quite slowly cut drinks off the booze tab
- Steward, at end of event, remarkably tanned
- Page number desperate chap located in a speed competition
- Turn up with a six-footer as escort
- Accompanying worker after a race to finish
- Escort nurse pinched by workers, the leader being nameless
Buddy explains!

The straight part
We know that "Waiter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case waiter = attendant.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 ATTENDANT mean?
ATTENDANT noun- One who attends; one who works with or watches over something.
- A servant or valet.
- A visitor or caller.
- That which accompanies or follows.
- One who owes a duty or service to another.
- Going with; associated; concomitant.
- Depending on, or owing duty or service to.