Grain appendage (3)
I believe the answer is:
awn
'grain appendage' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for awn that I've seen before include "bit of cereal" , "Bristle-like appendage on grass" , "Bristle on cereal spike" , "Beard growing from an ear of barley or rye" , "Beard of plant" .)