'stockholder' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
This is the entire clue.
Can you help me to learn more?
(Other definitions for storekeeper that I've seen before include "Stockroom employee" , "One looking after goods" , "One in charge of, eg, warehouse" , "Person responsible for stocks" , "Warehouse worker" .)
(Other definitions for pot that I've seen before include "Kitty; marijuana" , "Saucepan" , "Cooking vessel, plant container and street drug" , "prize" , "Street name for marijuana" .)