I say! Look! (3)
I believe the answer is:
eye
I believe this is a double definition.
'i' is the first definition.
(I've seen this in other clues)
'look' is the second definition.
(I know that eye is a type of look)
'say' acts as a link.
(Other definitions for eye that I've seen before include "Orb" , "Light-detector" , "Regard" , "Twenty four ac emphasises it" , "Ogle" .)