The most common and most likely answer to this crossword clue is the 4 letter word PICA
P
I
C
A
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The straight part
We know that "11 of 9/11 of 9" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case 11 of 9/11 of 9 = pica.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 PICA mean?
PICA noun- A disorder characterized by craving and appetite for non-edible substances, such as ice, clay, chalk, dirt, or sand.
- A size of type between small pica and English, standardized as 12-point.
- (usually with qualifier) A font of this size.
- A unit of length equivalent to 12 points, officially 35/83 cm (0.166 in) after 1886 but now 1/6 in.
- A pie or directory: the book directing Roman Catholic observance of saints' days and other feasts under various calendars.
- Any of several small, furry mammals, similar to guinea pigs, but related to rabbits, of the family Ochotonidae, from the mountains of North America and Asia.
- A magpie.