The most common and most likely answer to this crossword clue is the 8 letter word INCISIVE
I
N
C
I
S
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Buddy explains!
The straight part
We know that "Astute" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case astute = incisive.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 INCISIVE mean?
INCISIVE adjective- Quickly proceeding to judgment and forceful in expression; decisive; forthright.
- Intelligently analytical and concise.
- Having the quality of incising, cutting, or penetrating, as with a sharp instrument; sharp; acute; sarcastic; biting.
- Of or relating to the incisors.