Most properly, a well-known name (7)
I believe the answer is:
maxwell
'name' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'most properly a well-known' is the wordplay.
I cannot quite understand how this works, but
'most' could be 'max' (maximum) and 'max' is present in the answer.
'a well' could be 'well' and 'well' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for maxwell that I've seen before include "Victorian scientist" , "Robert, once a press baron" , "Pioneer of electromagnetism - Czech-born tycoon" , "Czech-born British publisher, d. at sea 1991" , "James Clerk --, Scottish physicist" .)