Anger after second month with a fever (7)
I believe the answer is:
febrile
'with a fever' is the definition.
(febrile can mean having a fever)
'anger after second month' is the wordplay.
'anger' becomes 'rile' (I've seen this before).
'after' is a charade indicator (letters next to each other).
'second month' becomes 'feb' (abbreviation for February).
'rile' put after 'feb' is 'FEBRILE'.
(Other definitions for febrile that I've seen before include "Showing nervous excitement" , "Delirious" , "Very hot" , "Nervously excited" , "Unhealthily excited" .)