Brown more stupid to get rid of gold ultimately (5)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

[d] UMBER (more stupid), without the D which is the last letter (ultimately) of [gol] D . The surface apparently refers to former UK Prime Minister Gordon Brown, who sold a large chunk of the country’s gold reserves while Chancellor of the Exchequer. Brown pigment derived from metal oxides.