Round gold coin (5)
I believe the answer is:
orbit
'round' is the definition.
(I've seen this before)
'gold coin' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'coin' becomes 'bit' (term for various historical coins).
'or'+'bit'='ORBIT'
(Other definitions for orbit that I've seen before include "Circle - influence" , "Circumnavigate" , "Satellite's path" , "Track of satellite" , "Circling path" .)