Trace mislaid box (5)
I believe the answer is:
crate
'box' is the definition.
(I know that crate is a type of box)
'trace mislaid' is the wordplay.
'mislaid' is an anagram indicator.
'trace' with letters rearranged gives 'CRATE'.
(Other definitions for crate that I've seen before include "Dilapidated vehicle" , "Packing-case made of wooden slats" , "Packing case with wooden slats" , "Car that will hardly go" , "Old soldiers might be found in this" .)