The most common and most likely answer to this crossword clue is the 4 letter word BOOR
I've seen this crossword clue in Independent
B
O
O
R
More clues leading to the result BOOR
- Voice disapproval of Republican oik
- Ill-mannered guy - show disapproval
- Brute, tiresome person in conversation
- Lout in black jumper turned up
- Yahoo loves taking over area in pub
- Barbarian begins bowing out of rugby
- Show contempt before Republican philistine
- Jeer Republican philistine
- Unpleasant person demolished centre of south coast resort
- Rowdy person born in the late Forties? Not Giovanni
Buddy explains!

The straight part
We know that "Yahoo" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case yahoo = boor.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 BOOR mean?
BOOR noun- A peasant.
- A Boer, white South African of Dutch or Huguenot descent.
- A yokel, country bumpkin.
- An uncultured person.