Mentioning an old saw (6)
I believe the answer is:
saying
'saw' is the definition.
(a saw can mean a proverb or maxim)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for saying that I've seen before include "Expressing in words" , "Articulating" , "Speaking; twenty-two Ac" , "Well-known phrase or proverb - just speaking" , "Motto" .)