Anger with a disease (7)
I believe the answer is:
cholera
'disease' is the definition.
(cholera is a kind of disease)
'anger with a' is the wordplay.
'anger' becomes 'choler' ('choler' can be a synonym of 'anger'**).
'with' means one lot of letters go next to another.
'choler'+'a'='CHOLERA'
(Other definitions for cholera that I've seen before include "Infectious disease causing severe bowel upset" , "Oh, Clare has highly infectious disease" , "Disease contracted from infected water" , "Contagious disease" , "could kill you" .)