Son fell, having tripped (8)
I believe the answer is:
stumbled
This clue might be a double definition.
'son fell' is the first definition.
The answer and definition can be both to do with motion as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?
'tripped' is the second definition.
('stumble' can be a synonym of 'trip')
'having' acts as a link.
Can you help me to learn more?
(Other definitions for stumbled that I've seen before include "Missed a step and almost fell" , "Tripped, faltered" , "Missed a step and nearly fell" , "Lost one's footing" , "Momentarily tripped" .)