Parking out of town? Nearly all is private (9)
I believe the answer is:
innermost
'private' is the definition.
(thesaurus)
'parking out of town? nearly all' is the wordplay.
'parking' becomes 'p'.
'out of' suggests deleting specific letters.
'town?' becomes 'pinner' (Greater London town).
'nearly all' becomes 'most'.
'pinner' with 'p' removed is 'inner'.
'inner'+'most'='INNERMOST'
'is' acts as a link.
(Other definitions for innermost that I've seen before include "Furthest in" , "Sort of secrets" , "Who may have gone deepest" , "Closest to the centre" , "Private" .)