Microwave, informally (4)
I believe the answer is:
nuke
'microwave informally' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nuke that I've seen before include "Drop huge bomb on" , "Nuclear weapon (sl.)" , "Attack with an atomic weapon" , "Attack with H-bomb (slang abbr.)" , "Destroy with a very powerful 18" .)