He was a bit of a blighter to a historic Christian (5)
I believe the answer is:
bligh
'he was a bit of a blighter to a historic christian' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for bligh that I've seen before include "Vice admiral" , "old captain dismissed" , "HMS Bounty captain" , "HMS Bounty's captain" , "Sea captain" .)