The most common and most likely answer to this crossword clue is the 8 letter word BABIRUSA
I've seen this crossword clue in Financial Times
B
A
B
I
R
U
S
A
Buddy explains!

The straight part
We know that "pig" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pig = babirusa.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 BABIRUSA mean?
BABIRUSA noun- Any of several mammals in the genus Babyrousa in the pig family Suidae, in which the upper tusk grows upward.