Start on DAR.org and once you locate his record you can click on the various children you can find more, which you then would confirm elsewhere.
It appears that he had Adam, Isaac, Rachel, Elizabeth etc. etc
http://services.dar.org/public/dar_research/search_adb/?action=full&p_id=A022963
CLEMENT, BENJAMIN Ancestor #: A022963
Service: VIRGINIA Rank: PATRIOTIC SERVICE
Birth: (CIRCA) 1700 KING WILLIAM CO VIRGINIA
Death: (ANTE) 4-18-1780 CLEMENT HILL PITTSYLVANIA CO VIRGINIA Service Source: CLEMENT, THE HIST OF PITTSYLVANIA CO,VA, PP 144-5
Service Description: 1) MANUFACTURER OF GUNPOWDER, 1775
SPOUSE: SUSANNA HILL
