Body in a box? (5)
I believe the answer is:
trunk
I believe this is a double definition.
'body' is the first definition.
(I know that body can be written as trunk)
'a box?' is the second definition.
(thesaurus)
'in' is the link.
(Other definitions for trunk that I've seen before include "Elephant's nose" , "Bole" , "Main body - chest" , "Travellers chest" , "Large storage box" .)