Try to get a free ride because of setback (5)
I believe the answer is:
hitch
'setback' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hitch that I've seen before include "Unforeseen obstacle" , "Unexpected problem" , "Temporary problem" , "Marry" , "To travel without paying" .)