De Beers business (6)
I believe the answer is:
mining
'de beers business' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mining that I've seen before include "Extracting ores or coal from the earth" , "Laying down explosives" , "Excavating (coal, ore)" , "Extracting ore etc. from the earth" , "Excavating (ores)" .)