But it's not an impediment to getting a lift (5)
I believe the answer is:
hitch
'a lift' is the definition.
(I've seen this before)
I cannot 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 "unite" , "Thumb (a lift)" , "Hindrance" , "Unforeseen obstacle" , "Snag - free ride" .)