The most common and most likely answer to this crossword clue is the 7 letter word LEGATES
I've seen this crossword clue in The Guardian
L
E
G
A
T
E
S
Buddy explains!
The straight part
We know that "Ambassadors" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ambassadors = legates.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 LEGATES mean?
LEGATES noun- A deputy representing the pope, specifically a papal ambassador sent on special ecclesiastical missions.
- An ambassador or messenger.
- The deputy of a provincial governor or general in ancient Rome.