Second choice article in gold (5)
I believe the answer is:
other
'second' is the definition.
(I've seen this before)
'choice article in gold' is the wordplay.
'choice article' becomes 'the' (the definite article in English. I am not sure about the 'choice' bit.).
'in' indicates putting letters inside.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'the' put into 'or' is 'OTHER'.
Can you help me to learn more?
(Other definitions for other that I've seen before include "Different, disparate" , "Different; alternate" , "Different, not the same one or this one" , "Very unusual" , "Distinct" .)