Use it to see who's calling (7)
I believe the answer is:
spyhole
(Other definitions for spyhole that I've seen before include "Viewing device" , "feature of door?" , "Viewer (e.g. in door)" , "Small viewing port" .)
I've seen this clue in The Guardian.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free.
Check out my app
or
learn more
about the Crossword Genius project.