He comes in for ill-treatment (7)
I believe the answer is:
patient
'he comes in for ill-treatment' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he comes in for' is the wordplay.
'he' becomes 'pat' (I've seen this before).
'comes in for' becomes 'ient' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pat'+'ient'='PATIENT'
Can you help me to learn more?
(Other definitions for patient that I've seen before include "Person requiring medical care" , "Forgiving" , "Enduring trying circumstances with an even temper" , "Doctor's 'customer'" , "Long-suffering - one under treatment" .)