Gold seen in abundance in bog (6)
I believe the answer is:
morass
'bog' is the definition.
(morass is a kind of bog)
'gold seen in abundance' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'seen in' indicates putting letters inside.
'abundance' becomes 'mass'.
'or' placed into 'mass' is 'MORASS'.
'in' acts as a link.
(Other definitions for morass that I've seen before include "Muddled situation" , "Bog or swamp" , "Bog - situation hard to get out of" , "Bog; confused situation" , "Slough, bog" .)