Shopkeeper oddly voided voucher, I'm mad about it (6)
I believe the answer is:
grocer
'shopkeeper' is the definition.
(I know that grocer is a type of shopkeeper)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for grocer that I've seen before include "Market trader" , "Food shop" , "Dealer in foodstuffs and household goods" , "Merchant who sells foodstuffs" , "Chesterton's wicked tradesman" .)