With 63-Across, test for pupils (3)
I believe the answer is:
eye
(Other definitions for eye that I've seen before include "where the pupil is seated" , "Body organ" , "Observe narrowly" , "study" , "round hole in sewer?" .)
I believe the answer is:
eye
(Other definitions for eye that I've seen before include "where the pupil is seated" , "Body organ" , "Observe narrowly" , "study" , "round hole in sewer?" .)