Outfit wife dons to work on case (3-5,4)

'case' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?

'outfit wife dons to work' is the wordplay.
I cannot really see how this works, but
'outfit' could be 'suit' (suit is a type of outfit) and 'suit' is found in the answer.
'wife' could be 'w' (abbreviation) and 'w' is found in the answer.
'to' is found in the answer.
'work' could be 'piece' (eg a work of art is a piece) and 'piece' is found within the answer.
No letters remain.
This explanation may well be incorrect...

'on' is the link.

Can you help me to learn more?