A journey for threepence (4)
I believe the answer is:
trip
'a journey' is the definition.
(trip is a kind of journey)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for trip that I've seen before include "Device working a trap or alarm when stumbled over" , "Run - dance - tumble" , "Outing; stumble" , "Journey - miss one's footing" , "Journey, excursion" .)