Heavenly article used for cake decoration (8)
I believe the answer is:
angelica
'for cake decoration' is the definition.
(angelica stalks are used to decorate cakes)
'heavenly article' is the wordplay.
'heavenly' becomes 'angelic' (relating to angels or heaven).
'article' becomes 'a' (the indefinite article in English).
'angelic'+'a'='ANGELICA'
'used' acts as a link.
(Other definitions for angelica that I've seen before include "Decorative candied stalk" , "Nag Alice to get fragrant plant" , "Candied plant stem" , "Candied plant stalks" , "Aromatic plant" .)