Being great, perhaps, he had two names (6)
I believe the answer is:
alfred
'two names' is the definition.
The definition suggests a singular noun which matches the answer.
'being great perhaps he' is the wordplay.
I cannot quite understand how this works, but
'being' could be 'red' (red is a kind of being) and 'red' is found within the answer.
'he' could be 'alf' and 'alf' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'had' acts as a link.
Can you help me to learn more?
(Other definitions for alfred that I've seen before include "Ninth century king of Wessex" , "Cake-burning king" , "A great king of Wessex, d. 899" , "Royal one across burner" , "... the Great, 9th-century Anglo-Saxon king" .)