Which gives needle-sharp sight? (3)
I believe the answer is:
eye
'sight?' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for eye that I've seen before include "Bit of a potato (or a needle?)" , "Body organ" , "Centre of storm" , "Aperture" , "Place for pupil" .)