Unlimited time following gold fraud (8)
I believe the answer is:
impostor
'fraud' is the definition.
(synonyms)
'unlimited time following gold' is the wordplay.
'unlimited time following' becomes 'impost' (I can't justify this - if you can you should believe this answer much more).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'impost'+'or'='IMPOSTOR'
(Other definitions for impostor that I've seen before include "False claimant" , "One pretends to be someone else to deceive" , "phoney!" , "Fake figure" , "a fraud" .)