The most common and most likely answer to this crossword clue is the 10 letter word WAREHOUSES
I've seen this crossword clue in The Guardian
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Buddy explains!
The straight part
We know that "stores" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stores = warehouses.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 WAREHOUSES mean?
WAREHOUSES noun- A place for storing large amounts of products. In logistics, a place where products go to from the manufacturer before going to the retailer.
- To store in a warehouse or similar.
- To confine (a person) to an institution for a long period.
- To acquire and then shelve, simply to prevent competitors from acquiring it.