Refuse fine offer involving gold (6)
I believe the answer is:
forbid
'refuse' is the definition.
(thesaurus)
'fine offer involving gold' is the wordplay.
'fine' becomes 'f' (abbreviation).
'offer' becomes 'bid' ('bid' can be a synonym of 'offer').
'involving' means one lot of letters goes inside another.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'f'+'bid'='fbid'
'fbid' placed around 'or' is 'FORBID'.
(Other definitions for forbid that I've seen before include "Refuse permission, do not allow" , "Refuse permission, order not to" , "Ban" , "Interdict" , "Deny, prohibit" .)