The most common and most likely answer to this crossword clue is the 10 letter word CASSIOPEIA
I've seen this crossword clue in Independent
C
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A
More clues leading to the result CASSIOPEIA
- Spies entrap idiot, minor poet regularly following stars
- More than one star is so epic – ace, ace, fantastic!
- Exercise beyond Shakespearean lieutenant, one with a vain queen
- CIA spies trained to guard old American stars
- Stellar group in a society with unusual poise protected by agents
- Devious old CIA spies on American stars
- “African Queen” is a Picasso, i.e., abstract
- Character in Othello reported noble group of stars
Buddy explains!
The straight part
We know that "vain queen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vain queen = cassiopeia.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.