Fleeing fog, chemist is collected by comrade in chopper (7)
I believe the answer is:
machete
'chopper' is the definition.
(blade for chopping things down)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for machete that I've seen before include "The mace (anag.)" , "Jungle blade" , "Jungle chopper" , "Heavy knife used as weapon" , "cutter" .)