The most common and most likely answer to this crossword clue is the 10 letter word OVERACTING
I've seen this crossword clue in The Guardian
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More clues leading to the result OVERACTING
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 OVERACTING mean?
OVERACTING verb- To act in an exaggerated manner.
- To act upon, or influence, unduly.