Legendary nobleman's legacy? 'Twas mine, in essence (6)
I believe the answer is:
gawain
'legendary nobleman's legacy?' is the definition.
The definition suggests a singular noun which matches the answer.
''twas mine in essence' is the wordplay.
I cannot quite understand how this works, but
'in' is found in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gawain that I've seen before include "round a table for him and his comrades?" , "Arthurian knight of the Round Table" , "Man at round table" , "One of King Arthur's knights" , "K" .)