A case that may be looked into (5)
I believe the answer is:
crate
'a case' is the definition.
(thesaurus)
'may be looked into' is the wordplay.
I cannot quite understand how this works, but
'be' could be 'rate' (rating is a kind of being) and 'rate' is found within the answer.
A single letter 'c' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'that' is the link.
Can you help me to learn more?
(Other definitions for crate that I've seen before include "Old soldiers might be found in this" , "Wooden box" , "Carton; old plane" , "Packing-case made of wooden slats" , "Packing case with wooden slats" .)