Gold coin in circulation? (5)
I believe the answer is:
orbit
'in circulation?' 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' (I've seen this before).
'or'+'bit'='ORBIT'
(Other definitions for orbit that I've seen before include "E.g. planetary movement" , "Circular path of a planet" , "Rotating path" , "Path of planet around sun" , "Revolution" .)