Door or lock opener (3)
I believe the answer is:
key
(Other definitions for key that I've seen before include "Device for lock" , "Clue" , "Crucial arch-stone" , "(3)" , "Piano lever" .)
I believe the answer is:
key
(Other definitions for key that I've seen before include "Device for lock" , "Clue" , "Crucial arch-stone" , "(3)" , "Piano lever" .)