Free parking in university before noon (5)
I believe the answer is:
unpin
'free' is the definition.
(I've seen this before)
'parking in university before noon' is the wordplay.
'parking' becomes 'p' (abbreviation on road signs).
'in' is an insertion indicator.
'university' becomes 'uni' (informal abbreviation).
'before' means one lot of letters go next to another.
'noon' becomes 'n' (abbreviation).
'p' placed inside 'uni' is 'unpi'.
'unpi'+'n'='UNPIN'
(Other definitions for unpin that I've seen before include "Things tied together" , "release" , "Loosen" , "free" , "Remove fastening from" .)