Gold, sir, returns a fragrance (5)
I believe the answer is:
orris
'a fragrance' is the definition.
'gold sir returns' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'returns' shows that the letters should be reversed in order.
'sir' backwards is 'ris'.
'or'+'ris'='ORRIS'
(Other definitions for orris that I've seen before include "Percussion instrument" , "Fragrant root used in perfumery" , "Iris with fragrant rhizome" , "Preparation" , "Type of flower" .)