The most common and most likely answer to this crossword clue is the 3 letter word MAD
I've seen this crossword clue in Independent
M
A
D
More clues leading to the result MAD
Buddy explains!

The straight part
We know that "Wild" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wild = mad.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 MAD mean?
MAD verb- To be or become mad.
- To madden, to anger, to frustrate.
- Insane; crazy, mentally deranged.
- (chiefly US; informal in UK) Angry, annoyed.
- Bizarre; incredible.
- Wildly confused or excited.
- Extremely foolish or unwise; irrational; imprudent.
- (usually with for or about) Extremely enthusiastic about; crazy about; infatuated with; overcome with desire for.
- (of animals) Abnormally ferocious or furious; or, rabid, affected with rabies.
- (chiefly Northeastern US) Intensifier, signifies an abundance or high quality of a thing; very, much or many.
- (of a compass needle) Having impaired polarity.
- Intensifier; to a large degree; extremely; exceedingly; very; unbelievably.