Old university graduate keeps on penning journal (7)
I believe the answer is:
bologna
'old university' is the definition.
(the University of Bologna was founded in 1088)
'graduate keeps on penning journal' is the wordplay.
'graduate' becomes 'BA' (someone with a Bachelor of Arts degree).
'keeps' indicates putting letters inside.
'penning' means one lot of letters goes inside another.
'journal' becomes 'log' (I've seen this in another clue).
'on' going around 'log' is 'ologn'.
'ba' enclosing 'ologn' is 'BOLOGNA'.
(Other definitions for bologna that I've seen before include "Italian province" , "Capital of Emilia-Romagna" , "North Italian university city" , "Italian city - smoked sausage" .)