Graduate song acquiring large complaint (7)
I believe the answer is:
malaria
'complaint' is the definition.
(malaria is a kind of disease)
'graduate song acquiring large' is the wordplay.
'graduate' becomes 'MA' (abbreviation for Master of Arts).
'song' becomes 'aria' (piece of music in an opera).
'acquiring' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'ma'+'aria'='maaria'
'maaria' going around 'l' is 'MALARIA'.
(Other definitions for malaria that I've seen before include "Fever-inducing disease" , "Tropical disease" , "Mosquito-borne disease" , "Protozoal disease" , "Disease from bites by infected mosquitoes" .)