Advanced, complex maths generating complaint (6)
I believe the answer is:
asthma
'complaint' is the definition.
(asthma is a medical complaint)
'advanced complex maths' is the wordplay.
'advanced' becomes 'a' (abbreviation).
'complex' indicates anagramming the letters.
'maths' with letters rearranged gives 'sthma'.
'a'+'sthma'='ASTHMA'
'generating' is the link.
(Other definitions for asthma that I've seen before include "inspiring trouble" , "Chronic breathing condition" , "Mat has difficult breathing" , "which leaves one breathless" , "Bronchial allergy" .)