Resting place of King Arthur (6)
I believe the answer is:
avalon
'resting place of king arthur' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for avalon that I've seen before include "Where King Arthur was conveyed after death" , "Isle of Celtic myth" , "Blessed Celtic isle" , "King Arthur's burial place" , "Place where King Arthur was brought after death" .)