Lay to rest in the hinterlands (5)
I believe the answer is:
inter
'lay to rest' is the definition.
('inter' can be a synonym of 'lay to rest')
'in the hinterlands' is the wordplay.
'in' indicates a hidden word.
'INTER' can be found hidden inside 'hinterlands'.
(Other definitions for inter that I've seen before include "promoting cessation" , "Set deep" , "team from Italy" , "Milan FC" , "Inhume" .)