The most common and most likely answer to this crossword clue is the 9 plus 2 plus 6 letter word CATHERINE OF ARAGON
I've seen this crossword clue in The Times
C
A
T
H
E
R
I
N
E
O
F
A
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G
O
N
Buddy explains!
The straight part
We know that "Old queen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old queen = catherine of aragon.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.