Oliver —, Lord Protector (8)
I believe the answer is:
cromwell
This clue is a double definition.
'oliver' is the first definition.
(I know that oliver can be written as Cromwell)
'lord protector' is the second definition.
(I've seen this before)
(Other definitions for cromwell that I've seen before include "Lord Protector (sixteen fifty three to sixteen fifty eight)" , "He gave the Irish the choice of going ''to hell or to Connacht''" , "Oliver --, Lord Protector" , "Roundhead leader" , "Old English statesman" .)