Incisor or canine, eg (5)
I believe the answer is:
tooth
This clue is a double definition.
'incisor' is the first definition.
(I've seen this before)
'canine eg' is the second definition.
(canine is a kind of tooth)
(Other definitions for tooth that I've seen before include "Eg, molar" , "Let it stand" , "Gearwheel cog" , "Taste" , "In which the old are long" .)