Lancelot's son (7)
I believe the answer is:
galahad
'lancelot's son' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for galahad that I've seen before include "K" , "Person of great nobility" , "Round Table knight of immaculate purity" , "Noble fellow" , "man of great virtue" .)