Old writer and editor at university talked freely (6,2)
I believe the answer is:
opened up
'talked freely' is the definition.
('open up' can be a synonym of 'talk freely')
'old writer and editor at university' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'writer' becomes 'pen' (I've seen this before).
'and' means one lot of letters go next to another.
'editor' becomes 'ed'.
'at university' becomes 'up'.
'o'+'pen'+'ed'+'up'='OPENED UP'
(Other definitions for opened up that I've seen before include "started shooting" , "Offered a freer view" , "Poured heart out" , "started talking" , "made disclosure" .)