Weapon guerrilla leader stuck in fellow (7)
I believe the answer is:
machete
'weapon' is the definition.
(machete is a kind of weapon)
'guerrilla leader stuck in fellow' is the wordplay.
'guerrilla leader' becomes 'che' (I've seen this in other clues).
'stuck in' is an insertion indicator.
'fellow' becomes 'mate' (I've seen this in other clues).
'che' put into 'mate' is 'MACHETE'.
(Other definitions for machete that I've seen before include "Cheat me over broad heavy knife used in jungle" , "Heavy South American knife" , "The mace (anag.)" , "hacker" , "cutter" .)