The most common and most likely answer to this crossword clue is the 10 letter word FASTIDIOUS
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Buddy explains!

The straight part
We know that "Meticulous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case meticulous = fastidious.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 FASTIDIOUS mean?
FASTIDIOUS adjective- Excessively particular, demanding, or fussy about details, especially about tidiness and cleanliness.
- Overly concerned about tidiness and cleanliness.
- Difficult to please; quick to find fault.