Round Table knight (8)
I believe the answer is:
lancelot
'round table knight' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lancelot that I've seen before include "One of King Arthur's knights, lover of Guinevere" , "queen's lover" , "Call tone for knight of Arthurian legend" , "Round Table member" , "'Knight of the round table, Guinevere's lover (8)'" .)