Missed a step and almost fell (8)
I believe the answer is:
stumbled
'missed a step and almost fell' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for stumbled that I've seen before include "Tripped, faltered" , "Momentarily tripped" , "Lost one's footing" , "Missed a step and nearly fell" , "Lost balance in walking or speaking" .)