Tool; old saying (3)
I believe the answer is:
saw
I believe this is a double definition.
'tool' is the first definition.
(I know that saw is a type of power tool)
'old saying' is the second definition.
(I've seen this in another clue)
(Other definitions for saw that I've seen before include "A maxim with teeth" , "The saying for cutting wood" , "Perceived visually" , "Understood" , "Grasped" .)