The most common and most likely answer to this crossword clue is the 10 letter word SADDLEBACK
I've seen this crossword clue in The Daily Telegraph
S
A
D
D
L
E
B
A
C
K
More clues leading to the result SADDLEBACK
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 = saddleback.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 SADDLEBACK mean?
SADDLEBACK noun- A saddle-shaped ridge forming a shallow pass between two peaks.
- A roof in the same shape, having a gable at each end.
- A coping that is thicker in the middle than at the edges.
- Any of various creatures having a saddle-shaped marking on the back.
- A breed of pig which is black with a pink saddle-shaped marking.
- An anticline.
- The great black-backed gull.
- The bird Philesturnus carunculatis.
- A variety of domestic goose.
- A raccoon oyster.
- The harp seal.
- The larva of the bombycid moth.
- Saddle-backed
- Saddle-backed
- To engage in anal sex with the intention of preserving one's virginity (chiefly by Christian teenagers)