Spike gets to twist someone's arm from the start in a sensitive spot (8,5)
I believe the answer is:
pressure point
'spike gets to twist someone's arm from the start' is the definition.
I can't judge whether this definition defines the answer.
'a sensitive spot' is the wordplay.
'a sensitive' becomes 'pressure' (I can't explain this - if you can you should give a lot more credence to this answer).
'spot' becomes 'point' ('point' can be a synonym of 'spot').
'pressure'+'point'='PRESSURE POINT'
'in' is the link.
Can you help me to learn more?
(Other definitions for pressure point that I've seen before include "Focus for shiatsu" , "Place where artery may be squeezed to stop bleeding" .)