The most common and most likely answer to this crossword clue is the 10 letter word RED-CARPET
I've seen this crossword clue in Independent
R
E
D
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C
A
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P
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T
More clues leading to the result RED-CARPET
Buddy explains!
The straight part
We know that "Top treatment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case top treatment = red-carpet.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 RED-CARPET mean?
RED-CARPET adjective- Ostentatiously special; VIP