The most common and most likely answer to this crossword clue is the 9 letter word TRUMPETED
I've seen this crossword clue in Financial Times
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More clues leading to the result TRUMPETED
Buddy explains!

The straight part
We know that "proclaimed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case proclaimed = trumpeted.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 TRUMPETED mean?
TRUMPETED verb- To sound loudly, be amplified
- To play the trumpet.
- Of an elephant, to make its cry.
- To give a loud cry like that of an elephant.
- To proclaim loudly; to promote enthusiastically