Decree in gold and possibly red (5)
I believe the answer is:
order
'decree' is the definition.
('order' can be a synonym of 'decree')
'gold and possibly red' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'and' says to put letters next to each other.
'possibly' is an anagram indicator.
'red' anagrammed gives 'der'.
'or'+'der'='ORDER'
'in' acts as a link.
(Other definitions for order that I've seen before include "an answer to all clues, initially" , "One may be tall if demanding" , "Call" , "Apply for - class" , "Religious fraternity" .)