Outfit selected from stock items (3)
I believe the answer is:
kit
'outfit' is the definition.
(I know that kit is a kind of outfit)
'selected from stock items' is the wordplay.
'selected from' indicates a hidden word.
'KIT' can be found hidden inside 'stock items'.
(Other definitions for kit that I've seen before include "Apparatus" , "Necessary equipment" , "Equipment, clothing" , "Set of tools or clothes" , "Supplies" .)