Somehow unrested, set to come out at night (8)
I believe the answer is:
dentures
'set to come out at night' is the definition.
'somehow unrested' is the wordplay.
'somehow' is an anagram indicator.
'unrested' is an anagram of 'DENTURES'.
(Other definitions for dentures that I've seen before include "Underset in teeth" , "Set of false teeth" , "Sets of artificial teeth." .)