Evil mogul accepting graduate's complaint (7)
I believe the answer is:
lumbago
'complaint' is the definition.
(I've seen this before)
'evil mogul accepting graduate's' is the wordplay.
'evil' is an anagram indicator.
'accepting' is an insertion indicator (inserted letters are accepted).
'graduate' becomes 'BA' (someone with a Bachelor of Arts degree).
'mogul' anagrammed gives 'lumgo'.
'lumgo' going around 'ba' is 'LUMBAGO'.
(Other definitions for lumbago that I've seen before include "Form of backache" , "Back complaint" , "Gaul mob (anag.)" , "Lower back ache" , "Rheumatic backache" .)