Box of vital personal possessions (5)
I believe the answer is:
chest
'box' is the definition.
(chest is a kind of box)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for chest that I've seen before include "Trunk or crate" , "Rib area" , "Bra on it" , "Coffer; trunk" , "Piece of furniture" .)