On which excursionists make mistakes? (5)
I believe the answer is:
trips
'mistakes?' is the definition.
(trip is a kind of mistake)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for trips that I've seen before include "Stumbles or triggers" , "Stumbles on short journeys?" , "is hallucinating" , "Journeys or excursions" , "Outings" .)