Lay to rest in Hinterland (5)
I believe the answer is:
inter
'lay to rest' is the definition.
(synonyms)
'in hinterland' is the wordplay.
'in' says the answer is hidden in the clue.
'INTER' is hidden within 'hinterland'.
(Other definitions for inter that I've seen before include "football team abroad" , "Set deep" , "Entomb" , "Nitre (anag.)" , "team from Italy" .)