Order latches, in case (7)
I believe the answer is:
satchel
'case' is the definition.
(satchel is a kind of case)
'order latches' is the wordplay.
'order' indicates an anagram.
'latches' anagrammed gives 'SATCHEL'.
'in' is the link.
(Other definitions for satchel that I've seen before include "What's carried by pupils" , "Shoulder bag as for schoolbooks" , "Get school item" , "Carrier for school books" , "Schoolbag for children's books" .)