Idiot cancelled having heart transplant (3)
I believe the answer is:
oaf
'idiot' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for oaf that I've seen before include "Oik" , "Idiot" , "Boor or lout" , "Stupid lout" , "buffoon" .)