"The King” (5)
'the king' is the definition.
(I have seen 'The King' mean 'elvis' so perhaps 'king' could also mean 'elvis')
This is all the clue.
(Other definitions for elvis that I've seen before include "Stop!" , "Singers Presley or Costello" , "Legendary singer" , "The familiar King of rock music" , "Singer Presley" .)