Consequences of pursuing US subject (9)
I believe the answer is:
aftermath
'consequences' is the definition.
(I've seen this before)
'pursuing us subject' is the wordplay.
'pursuing' becomes 'after' (I've seen this before).
'us subject' becomes 'math' (mathematics).
'after'+'math'='AFTERMATH'
'of' acts as a link.
(Other definitions for aftermath that I've seen before include "Subsequent consequences" , "Sequel" , "Consequence of an event, situation that follows" , "Frame that in following events" , "Consequences of a bad event" .)