Thing that time changes (4)
I believe the answer is:
item
'thing' is the definition.
(thesaurus)
'time changes' is the wordplay.
'changes' is an anagram indicator.
'time' is an anagram of 'ITEM'.
'that' is the link.
(Other definitions for item that I've seen before include "Entry (in an account)" , "Romantic couple" , "story" , "Two lovers as one" , "One thing on a list" .)