The most common and most likely answer to this crossword clue is the 10 letter word DISCERNING
I've seen this crossword clue in The Daily Telegraph
D
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More clues leading to the result DISCERNING
Buddy explains!

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 DISCERNING mean?
DISCERNING verb- To detect with the senses, especially with the eyes.
- To perceive, recognize, or comprehend with the mind; to descry.
- To distinguish something as being different from something else; to differentiate.
- To perceive differences.
- Discernment
- Of keen insight or good judgement; perceptive.