Tool store (4)
I believe the answer is:
file
This clue is a double definition.
'tool' is the first definition.
(file is a kind of tool)
'store' is the second definition.
(I've seen this in another clue)
(Other definitions for file that I've seen before include "Three Dn and this can indicate ordinary people" , "(Set of) documents- line" , "Set of papers" , "Tool for sawing through metal" , "Smoothing tool; organised data" .)