Body found in restroom at terminus (6)
I believe the answer is:
matter
'body' is the definition.
(thesaurus)
'in restroom at terminus' is the wordplay.
'in' indicates a hidden word.
'MATTER' is hidden within 'restroom at terminus'.
'found' is the link.
(Other definitions for matter that I've seen before include "Affair; be important" , "Physical substance" , "Be of significance" , "Substance; topic" , "It has mass and occupies space" .)