The most common and most likely answer to this crossword clue is the 6 letter word VANDAL
I've seen this crossword clue in The Times
V
A
N
D
A
L
More clues leading to the result VANDAL
- Yahoo is cutting edge? Contrarily juvenile
- Vehicle picked up juvenile delinquent
- Destructive lout beginning to lurk behind London museum
- Old German museum, large
- Destructive type left at rear of London museum
- One attacking art lecturer attached to London museum
- Old German destroyer still active today
- Person wantonly damaging property in museum close to Whitehall
- Wrecker of vehicle boy overturned
- Damager of London museum going on trial at last
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 = vandal.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 VANDAL mean?
VANDAL noun- A person who needlessly destroys, defaces, or damages other people's property.