The nerve! Torturous CIA tickled prisoners (7)
I believe the answer is:
sciatic
'the nerve' is the definition.
(sciatic nerve is a kind of nerve)
'torturous cia tickled prisoners' is the wordplay.
'SCIATIC' is hidden in amongst the letters.
However, I'm unsure how this is indicated.
Can you help me to learn more?
(Other definitions for sciatic that I've seen before include "Relating to the hip or to pain around the body's longest nerve" , "(Of a nerve) in the region of the hip" , "Largest nerve in the body" , "Nerve connected with back pain" , "Relating to a nerve of the lower back" .)