Over in Paris, it is uni study which causes a headache (9)
I believe the answer is:
sinusitis
'a headache' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'over in paris it is uni study which' is the wordplay.
'over' says the letters should be written in reverse.
'in' says the answer is hidden in the clue.
'sitisunis' can be found hidden inside 'paris it is uni study which'.
'sitisunis' reversed gives 'SINUSITIS'.
'causes' is the link.
Can you help me to learn more?
(Other definitions for sinusitis that I've seen before include "Nasal membrane inflammation" , "Inflammation of nasal cavities" , "Inflammation of head cavities" , "nasal problem" , "Inflammation in the skull" .)