The most common and most likely answer to this crossword clue is the 10 letter word ILLUMINATE
I've seen this crossword clue in Independent
I
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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 ILLUMINATE mean?
ILLUMINATE noun- Someone thought to have an unusual degree of enlightenment.
- To shine light on something.
- To decorate something with lights.
- To clarify or make something understandable.
- To decorate the page of a manuscript book with ornamental designs.
- To make spectacular.
- To glow; to light up.
- To be exposed to light.
- To direct a radar beam toward.
- Enlightened