King in play destroying Borneo (6)
I believe the answer is:
oberon
'king in play' is the definition.
(king in Shakespeare's A Midsummer Night's Dream)
'destroying borneo' is the wordplay.
'destroying' is an anagram indicator.
'borneo' with letters rearranged gives 'OBERON'.
(Other definitions for oberon that I've seen before include "MND fairy king" , "Titania's consort" , "Shakespearean role" , "Titania's husband" , "top charmer!" .)