As medic, I locate some back pain (5)
I believe the answer is:
colic
'pain' is the definition.
(I know that colic is a type of pain)
'as medic i locate some back' is the wordplay.
'some' indicates a hidden word.
'back' says the letters should be written in reverse.
'ciloc' is hidden within 'as medic i locate'.
'ciloc' back-to-front is 'COLIC'.
(Other definitions for colic that I've seen before include "Abdominal pain from wind or obstruction" , "gut reaction" , "Abdominal pain suffered by babies and horses" , "Briefly, officer in charge makes a complaint" , "Abdominal pain, especially in infants" .)