A good friend introduces the revolutionary with the tool/knife (7)
I believe the answer is:
machete
'the toolknife' is the definition.
I can't judge whether this defines the answer.
'a good friend introduces the revolutionary' is the wordplay.
'a good friend' becomes 'mate' (mate is a kind of friend. I am not sure about the 'good' bit.).
'introduces' indicates putting letters inside.
'the revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'mate' going around 'che' is 'MACHETE'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for machete that I've seen before include "hacker" , "Jungle chopper" , "Heavy knife used as weapon" , "The mace (anag.)" , "Teach me with large jungle knife" .)