The most common and most likely answer to this crossword clue is the 10 letter word BLACKBALLS
B
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More clues leading to the result BLACKBALLS
Buddy explains!

The straight part
We know that "Vetoes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vetoes = blackballs.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 BLACKBALLS mean?
BLACKBALLS noun- A rejection; a vote against admitting someone.
- A black ball used to indicate such a negative vote.
- A kind of large black sweet; a niggerball.
- A substance for blacking shoes, boots, etc. or for taking impressions of engraved work.
- To vote against, especially in an exclusive organization.
- To ostracize.