The most common and most likely answer to this crossword clue is the 4 letter word HASH
H
A
S
H
Buddy explains!

The straight part
We know that "stew" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stew = hash.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 HASH mean?
HASH noun- Food, especially meat and potatoes, chopped and mixed together.
- A confused mess.
- The # symbol (octothorpe, pound).
- The result generated by a hash function.
- A new mixture of old material; a second preparation or exhibition; a rehashing.
- A hash run.
- A stupid fellow.
- To chop into small pieces, to make into a hash.
- To make a quick, rough version
- To transform according to a hash function.
- Hashish, a drug derived from the cannabis plant.