Old Greek university plugging dissertations (7)
I believe the answer is:
theseus
'old greek' is the definition.
'theseus' can be an answer for 'greek' (I have seen 'ancient Greek' mean 'theseus' so perhaps 'greek' could also mean 'theseus'). I am not certain of the 'old' bit.
'university plugging dissertations' is the wordplay.
'university' becomes 'U' (abbreviation for university).
'plugging' indicates putting letters inside (inserted letters plug up a gap in the word).
'dissertations' becomes 'theses' ('thesis' can be a synonym of 'dissertation').
'u' going into 'theses' is 'THESEUS'.
Can you help me to learn more?
(Other definitions for theseus that I've seen before include "Greek king" , "Heroic figure" , "Duke in A Midsummer Night's Dream" , "Heroic Greek" , "Occasion when public may visit (eg, school)" .)