Genuine gold article and tin mixed about (9)
I believe the answer is:
authentic
'genuine' is the definition.
(similar in meaning)
'gold article and tin mixed about' is the wordplay.
'gold' becomes 'Au' (Au is the chemical symbol for gold).
'article' becomes 'the' (the definite article in English).
'and' means one lot of letters go next to another.
'mixed' indicates an anagram.
'about' becomes 'c' (abbreviation for 'circa').
'tin' is an anagram of 'nti'.
'au'+'the'+'nti'+'c'='AUTHENTIC'
(Other definitions for authentic that I've seen before include "trustworthy" , "Bona fide" , "reliable" , "Genuine, not a copy" , "Ian, the cut is genuine" .)