Sailor, stabbed, doubled over (10)
I believe the answer is:
jackknifed
'doubled over' is the 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?
'sailor stabbed' is the wordplay.
'sailor' becomes 'jack' (informal term for a sailor).
'stabbed' becomes 'knifed' ('knife' can be a synonym of 'stab').
'jack'+'knifed'='JACKKNIFED'
Can you help me to learn more?
(Other definitions for jackknifed that I've seen before include "Doubled up" , "Accidentally folded (of a lorry)" .)