Sweetheart wearing golden jacket (5)
I believe the answer is:
gilet
'jacket' is the definition.
(a gilet is a sleeveless jacket)
'sweetheart wearing golden' is the wordplay.
'sweetheart' becomes 'e' (the heart/centre of 'sweet').
'wearing' indicates putting letters inside.
'golden' becomes 'gilt' (synonyms).
'e' put into 'gilt' is 'GILET'.
(Other definitions for gilet that I've seen before include "apparel" , "Body-warmer" , "Type of jacket" , "Waistcoat" , "Sleeveless padded jacket" .)