Cook traces boxes (6)
I believe the answer is:
crates
'boxes' is the definition.
(I know this)
'cook traces' is the wordplay.
'cook' is an anagram indicator.
'traces' anagrammed gives 'CRATES'.
(Other definitions for crates that I've seen before include "Jalopies" , "Boxes for shipping goods" , "Rough wooden boxes" , "Packing cases" .)