Severe beating, it gets inflammation (9)
I believe the answer is:
thrashing
'severe beating' is the definition.
'thrashing' can be an answer for 'beating' (synonyms). I'm not certain of the 'severe' bit.
'it gets inflammation' is the wordplay.
'it' becomes 'thing'.
'gets' is an insertion indicator (gets can mean captures or absorbs).
'inflammation' becomes 'rash' (I can't justify this - if you can you should give a lot more credence to this answer).
'thing' enclosing 'rash' is 'THRASHING'.
Can you help me to learn more?
(Other definitions for thrashing that I've seen before include "Hiding" , "punishment" , "A very heady defeat" , "beating" .)