Choice article in heraldic gold (5)
I believe the answer is:
other
'choice' is the definition.
Both the definition and answer are adjectives. Maybe there's an association between them I don't understand?
'article in heraldic gold' is the wordplay.
'article' becomes 'the' (the definite article).
'in' means one lot of letters goes inside another.
'heraldic gold' becomes 'or' ('or' is the heraldic name for gold. I am not sure about the 'heraldic' bit.).
'the' put inside 'or' is 'OTHER'.
Can you help me to learn more?
(Other definitions for other that I've seen before include "Different; alternate" , "Very unusual" , "Alternate; additional" , "Different, disparate" , "Different, alternative" .)