Incisive associate of Jack and Mack (5)
I believe the answer is:
knife
This clue could be a double definition.
'incisive associate of jack' is the first definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'mack' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'and' acts as a link.
Can you help me to learn more?
(Other definitions for knife that I've seen before include "Cutting tool" , "Potential weapon" , "Cutting implement - stab" , "Lethal weapon" , "Use this to carve" .)