Short knife for stabbing (6)
I believe the answer is:
dagger
'short knife for stabbing' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for dagger that I've seen before include "Short knife for stabbing" , "The weapon Macbeth thought he saw" , "Macbeth's weapon" , "that has an incisive point" , "A weapon; a reference mark" .)