Turncoat’s characteristic: wanting gold (7)
I believe the answer is:
traitor
'turncoat's' is the definition.
(I've seen this before)
'characteristic wanting gold' is the wordplay.
'characteristic' becomes 'trait' (I've seen this before).
'wanting' says to put letters next to each other.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'trait'+'or'='TRAITOR'
(Other definitions for traitor that I've seen before include "Unreliable type" , "Maclean was one" , "One betraying one's country" , "One committing treason" , "Rat displayed" .)