Refuse to allow fine gold offer (6)
I believe the answer is:
forbid
'refuse to allow' is the definition.
(I've seen this before)
'fine gold offer' is the wordplay.
'fine' becomes 'f' (abbreviation).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'offer' becomes 'bid' ('bid' can be a synonym of 'offer').
'f'+'or'+'bid'='FORBID'
(Other definitions for forbid that I've seen before include "Interdict" , "bar" , "Prohibit, veto" , "Outlaw" , "Refuse permission, order not to" .)