The most common and most likely answer to this crossword clue is the 8 letter word OVATIONS
O
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Buddy explains!

The straight part
We know that "signs of approval" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case signs of approval = ovations.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 OVATIONS mean?
OVATIONS noun- A victory ceremony of less importance than a triumph.
- (by extension) A (ceremony for the) recognition of some achievement.
- (by extension) Prolonged enthusiastic applause.
- To give (someone) an ovation (prolonged enthusiastic applause).