Cromwell's bodyguard? (9)
I believe the answer is:
Here is my best explanation:
This clue is a double definition.
'cromwell's' is the first definition.
(Oliver Cromwell was Lord Protector)
'bodyguard?' is the second definition.
(bodyguard is a kind of protector)
(Other definitions for protector that I've seen before include "Defender", "Box at Lord's say", "Patron" and "Guardian; regent".)