Antiquated brace in old vessel (7)
I believe the answer is:
outworn
'antiquated' is the definition.
(thesaurus)
'brace in old vessel' is the wordplay.
'brace' becomes 'two' (I've seen this before).
'in' means one lot of letters goes inside another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'vessel' becomes 'urn' (urn is a kind of vessel).
'o'+'urn'='ourn'
'two' inserted inside 'ourn' is 'OUTWORN'.
(Other definitions for outworn that I've seen before include "Old, exhausted or no longer used as dress" , "Out of date" , "Old-fashioned" , "Jaded" , "Obsolete, dated" .)