The most common and most likely answer to this crossword clue is the 7 letter word BANQUET
I've seen this crossword clue in Independent
B
A
N
Q
U
E
T
More clues leading to the result BANQUET
- Stop crusade to get rid of seconds in dinner party
- Mum disheartened after earl leaves beanfeast
- Black pipe down to bin I fill with food
- Outlaw still missing one meal
- Make illegal journey wanting society dinner with royalty?
- Spread Prohibition to Sleepy Hollow
- Wipe empty table at end of seat to eat
- We’re told save banter for lavish meal
- Encourage noise? I left for a formal dinner
- British worker eats what in Paris? Not petit déjeuner!
Buddy explains!

The straight part
We know that "dinner with royalty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dinner with royalty = banquet.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 BANQUET mean?
BANQUET noun- A large celebratory meal; a feast.
- A dessert; a course of sweetmeats.
- To participate in a banquet; to feast.
- To have dessert after a feast.
- To treat with a banquet or sumptuous entertainment of food; to feast.