Pen shop (4)
I believe the answer is:
coop
I believe this is a double definition.
'pen' is the first definition.
(I've seen this before)
'shop' is the second definition.
(short for The Co-operative Group)
(Other definitions for coop that I've seen before include "Store" , "box of chickens" , "Birdcage" , "Cage for poultry" , "pound" .)