A clearance sale is a sale in which the goods in a shop are sold at reduced prices, because the shopkeeper wants to get rid of them quickly or because the shop is closing down.
clearance sale in British English
(ˈklɪərəns seɪl)
noun
a sale of merchandise at reduced prices with a view to clearing it
The major clearance sales start next week.
clearance sale in American English
a sale to get rid of old merchandise and make room for new