Free university books inaccessible after vacation (5)
I believe the answer is:
untie
'free' is the definition.
(thesaurus)
'university books inaccessible after vacation' is the wordplay.
'university' becomes 'u'.
'books' becomes 'nt' (New Testament).
'after vacation' suggests removing the centre (the inside letters must vacate).
'inaccessible' with its centre taken out is 'ie'.
'u'+'nt'+'ie'='UNTIE'
(Other definitions for untie that I've seen before include "Free from binds" , "Undo a knot" , "Remove fastenings from" , "Separate" , "Disconnect; release" .)