Supermarket carts (8)
I believe the answer is:
trolleys
'supermarket carts' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for trolleys that I've seen before include "Vehicles" , "Handcarts that hold groceries" , "Supermarket carts" , "Tells Roy to get supermarket carriers" , "moving beds?" .)