Eliminate king in peace (5)
I believe the answer is:
erase
'eliminate' is the definition.
(I've seen this before)
'king in peace' is the wordplay.
'king' becomes 'r' (r is abbreviation for rex).
'in' indicates putting letters inside.
'peace' becomes 'ease' (I've seen this in other clues).
'r' put into 'ease' is 'ERASE'.
(Other definitions for erase that I've seen before include "Eradicate" , "Scratch" , "Take out" , "Blot out" , "Remove, wipe out" .)