Ultimately silent, private borough perhaps (4)
I believe the answer is:
town
'borough perhaps' is the definition.
(borough is a kind of town)
'ultimately silent private' is the wordplay.
'ultimately' says to take the final letters.
'private' becomes 'own' (as in one's own or private belongings).
The last letter of 'silent' is 't'.
't'+'own'='TOWN'
(Other definitions for town that I've seen before include "It lies between village and city" , "Community group" , "more established area with 1a [OLD]" , "See 1" , "SECOND PART OF 17" .)