Sight in glasses slightly reduced (9)
I believe the answer is:
spectacle
'sight' is the definition.
(I know that spectacle is a type of sight)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for spectacle that I've seen before include "worth looking at" , "Entertaining sight, they help to see in the plural" , "Wonder" , "sensational event" , "what may be regarded as > ridiculous" .)