The most common and most likely answer to this crossword clue is the 6 letter word VIZIER
I've seen this crossword clue in The Daily Telegraph
V
I
Z
I
E
R
More clues leading to the result VIZIER
- That is right, after that is official
- Foreign minister — namely, one to accompany Her Majesty
- Minister to wit: That’s right!
- Old court official — namely one standing over the Queen
- Muslim official that is to say one bedtime prayer finally
- Old court official, specifically one over the Queen
- Namely, one ruler’s foreign minister
- Councillor of state that’s repeatedly suppressing king
- That is to say that is right official
- Councillor, namely, that is linked to King
Buddy explains!

The straight part
We know that "Old court official" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old court official = vizier.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 VIZIER mean?
VIZIER noun- A high-ranking official or minister in an Islamic government, especially in the Ottoman Empire.
- Vicegerent, viceroy
- A fairy chess piece that can only be moved one space up, down, left or right.