The most common and most likely answer to this crossword clue is the 9 letter word CONCUSSED
I've seen this crossword clue in The Guardian
C
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More clues leading to the result CONCUSSED
Buddy explains!

The straight part
We know that "Partially conscious" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case partially conscious = concussed.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 CONCUSSED mean?
CONCUSSED verb- To injure the brain of, usually temporarily, by violent impact.
- To force to do something, or give up something, by intimidation; to coerce.
- Knocked out, temporarily confused or unconscious due to a blow to the head