Sharp canine (4)
I believe the answer is:
fang
'sharp canine' is the definition.
'fang' can be an answer for 'canine' (I've seen this before). I also know that 'sharp' relates to this answer.
This is the entire clue.
(Other definitions for fang that I've seen before include "Dracula's tooth?" , "Animal tooth" , "Wolf's tooth" , "Venom-tooth" , "Long pointed tooth" .)