Shuāngshíyī de shíhou, tā yìkǒuqì qīngkōng le gòuwùchē.
On Singles' Day she bought everything in her shopping cart in one go.
Tips
usage
清空 takes a container as its object: 清空回收站 (to empty the recycle bin), 清空缓存 (to clear the cache). 清空购物车 "to clear the shopping cart" usually means buying everything in it, not deleting it.
