Object to night work (5)
I believe the answer is:
thing
'object' is the definition.
(an object is a thing or item)
'night work' is the wordplay.
'work' is an anagram indicator.
'night' is an anagram of 'THING'.
'to' is the link.
(Other definitions for thing that I've seen before include "Inanimate object" , "Object; gadget" , "Affair - matter" , "Individual unit" , "Individual object" .)