Whiplash symptom? Headache (4,2,3,4)
I believe the answer is:
pain in the neck
This could be a double definition.
'whiplash' is the first definition.
(whiplash may cause neck pain)
'symptom? headache' is the second definition.
'pain in the neck' can be an answer for 'headache' (I've seen this before). I'm unsure of the 'symptom?' bit.
Can you help me to learn more?
(Other definitions for pain in the neck that I've seen before include "Really annoying person" , "bind" , "Torticollis" , "Persistently difficult person or thing (caused by a whiplash?)" , "Annoyance (colloq.)" .)