Insect delineated path leading to top of trench (6)
I believe the answer is:
locust
'insect' is the definition.
(locust is a kind of insect)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for locust that I've seen before include "Swarming grasshopper" , "Migratory crop stripper" , "beast resulting in destruction" , "Large insect" , "Swarming, devouring, insect" .)