Repercussions, following American subject (9)
I believe the answer is:
aftermath
'repercussions' is the definition.
(I've seen this before)
'following american subject' is the wordplay.
'following' becomes 'after' (following can mean after or as a result of).
'american subject' becomes 'math' (math is a kind of subject. I am not sure about the 'american' bit.).
'after'+'math'='AFTERMATH'
Can you help me to learn more?
(Other definitions for aftermath that I've seen before include "Consequences of an unpleasant event" , "Outcome of being at the farm" , "Circumstances that follow an event" , "What may be the later consequences" , "Subsequent consequences" .)