Putting up with pain (9)
I believe the answer is:
suffering
This clue is a double definition.
'putting up with' is the first definition.
('suffer' can be a synonym of 'put up with')
'pain' is the second definition.
(suffering is a kind of pain)
(Other definitions for suffering that I've seen before include "Experiencing pain" , "Hardship" , "Ailing" .)