Complaint of aunt finally in Austen novel (7)
I believe the answer is:
tetanus
'complaint' is the definition.
(tetanus is a kind of health problem)
'aunt finally in austen novel' is the wordplay.
'finally' indicates one should take the final letters.
'in' is an insertion indicator.
'novel' indicates anagramming the letters.
The last letter of 'aunt' is 't'.
'austen' anagrammed gives 'teanus'.
't' going into 'teanus' is 'TETANUS'.
'of' is the link.
(Other definitions for tetanus that I've seen before include "Bacterial disease" , "infectious disease" , "Disease known as lockjaw from rabid dog bite" , "Infection of the central nervous system" , "Locker" .)