Crossword Genius

What's in store at the chemist's? (4)

Ross

I believe the answer is:

drug

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'chemist's?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for drug that I've seen before include "Perhaps an upper" , "LSD, say" , "Chemical medicament" , "Substance used in medicine, often abused" , "Medication" .)

I've seen this clue in the Evening Standard.
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