Irate chum suffering with stiff joints (9)
I believe the answer is:
rheumatic
'with stiff joints' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'irate chum suffering' is the wordplay.
'suffering' 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 "Kind of fever - irate chum (anag)" , "Suffering from pain in muscles or joints" , "Affected by an inflammatory disease" , "someone ill from damp?" , "Type of muscle or joint pain" .)