The King lives dangerously (5)
I believe the answer is:
elvis
'the king' is the definition.
(I've seen this in another clue)
'lives dangerously' is the wordplay.
'dangerously' indicates an anagram (the letter order is damaged or endangered).
'lives' with letters rearranged gives 'ELVIS'.
(Other definitions for elvis that I've seen before include "Mister Presley for one" , "Lives for rock'n'roll king" , "Singers Presley or Costello" , "Stop!" , "Mr Presley" .)