Case (5)
'case' is the definition.
(I know that case can be written as instance)
This is all the clue.
(Other definitions for instance that I've seen before include "Canniest (anag) - occurrence" , "An insect (anag.)" , "Specimen" , "Case or example from ancients" , "Case in point" .)
'case' is the definition.
(I know that case can be written as sheath)
This is the entire clue.
(Other definitions for sheath that I've seen before include "Blade-cover" , "Case for a dagger" , "cocktail dress" , "coat" , "case for weapon" .)
'case' is the definition.
(I know that shell is a type of hull)
This is the entire clue.
(Other definitions for shell that I've seen before include "Crustacean's protection" , "A little pasta" , "pepper?" , "ammunition" , "Carapace or cartridge" .)
'case' is the definition.
(test case is a kind of case)
This is all the clue.
(Other definitions for test that I've seen before include "Check" , "Trial - international game" , "water flowing through Hampshire" , "Critical examination or trial of qualities or abilities" , "Trial; Hampshire river" .)