A small hole in a double-lidded organ (3)
I believe the answer is:
eye
'organ' is the definition.
(I know that eye is a type of sensory receptor)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for eye that I've seen before include "It accommodates a pupil" , "Sense organ" , "Four [NEEDLEFUL] may pass through this" , "Regard" , "One looks" .)