The most common and most likely answer to this crossword clue is the 8 letter word BOUILLON
B
O
U
I
L
L
O
N
More clues leading to the result BOUILLON
Buddy explains!

The straight part
We know that "soup" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case soup = bouillon.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 BOUILLON mean?
BOUILLON noun- A clear seasoned broth made by simmering usually light meat, such as beef or chicken.
- An excrescence on a horse's frush or frog.