The most common and most likely answer to this crossword clue is the 5 letter word GUMBO
I've seen this crossword clue in The Daily Telegraph
G
U
M
B
O
More clues leading to the result GUMBO
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 = gumbo.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 GUMBO mean?
GUMBO noun- A soup or stew made with okra.
- A fine silty soil that when wet becomes very thick and heavy.
- The edible immature mucilaginous seed pod (properly, capsule) of the Abelmoschus esculentus.
- The flowering mallow plant Abelmoschus esculentus itself, now commonly grown in the tropics and warmer parts of the temperate zones.