Bill includes broken chair that's antique (7)
I believe the answer is:
archaic
'antique' is the definition.
(thesaurus)
'bill includes broken chair' is the wordplay.
'bill' becomes 'ac'.
'includes' is an insertion indicator.
'broken' indicates anagramming the letters.
'chair' is an anagram of 'rchai'.
'ac' going around 'rchai' is 'ARCHAIC'.
'that's' acts as a link.
(Other definitions for archaic that I've seen before include "Obsolete" , "Outdated" , "Of a much earlier period" , "Antiquated" , "Primitive" .)