Irate chum twisted joint causing such pain (9)

I believe the answer is:

rheumatic

I'm a little stuck... Click here to teach me more about this clue!

'joint causing such pain' is the definition.
I can't tell whether this definition defines the answer.

'irate chum twisted' is the wordplay.
'twisted' indicates anagramming the letters.
'irate'+'chum'='iratechum'
'iratechum' with letters rearranged gives 'RHEUMATIC'.

Can you help me to learn more?

(Other definitions for rheumatic that I've seen before include "Like some painful muscles and joints" , "Suffering from pain in muscles or joints" , "suffering from cold and damp?" , "Kind of fever - irate chum (anag)" , "Creaking sounds" .)

I've seen this clue in the Irish Times (Crosaire) and the Irish Times.

Want a hint initially instead of a full solution? Install my app