I used to have a part time job where I taught English to the younger brother of that clerk.
That shop employee was a real kidder, wasn't he?
Well, while standing in the checkout line I heard one of the salespeople yell, "Shoplifter! Grab him!" so I grabbed him.
The shop member is someone who is a "member" (aka employed by) the shop. This is the shop staff.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.