Jar an old king put away (5)
I believe the answer is:
grate
'jar' is the definition.
(make unpleasant sound)
'an old king put away' is the wordplay.
'an old king' becomes 'GR' (Georgius Rex, Latin for King George).
'put away' becomes 'ate' (put away can mean to eat).
'gr'+'ate'='GRATE'
(Other definitions for grate that I've seen before include "Barred framework" , "Shred - jar" , "Grind, rasp" , "Great (anag.)" , "Grind (cheese)" .)