Leave in some pain (5)
I believe the answer is:
agony
'pain' is the definition.
(agony is a kind of pain)
'leave in some' is the wordplay.
'leave' becomes 'go' (to go is to depart or leave).
'in' is an insertion indicator.
'some' becomes 'any' (similar in meaning).
'go' placed into 'any' is 'AGONY'.
(Other definitions for agony that I've seen before include "Excruciating pain" , "Mental suffering" , "Really severe pain" , "woe" , "Intense pain" .)