Japanese staple (4)
I believe the answer is:
rice
'japanese staple' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rice that I've seen before include "Edible grains of grass" , "Cereal grown in paddy fields" , "Lyricist Tim - dramatist Elmer" , "Cereal food" , "Paddy field crop" .)