Trip, falter (7)
I believe the answer is:
stumble
This clue is a double definition.
'trip' is the first definition.
(I know that trip can be written as stumble)
'falter' is the second definition.
(synonyms)
(Other definitions for stumble that I've seen before include "Fall while walking or running" , "Falter" , "Momentarily trip" , "Trip and almost fall" , "Come near to falling while walking" .)