A new port somewhere in Hampshire (7)
I believe the answer is:
andover
'somewhere in hampshire' is the definition.
(town in Hampshire)
'a new port' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'port' becomes 'dover' (port town in Kent).
'a'+'n'+'dover'='ANDOVER'
(Other definitions for andover that I've seen before include "Town in Hampshire" , "New town development" , "Hants town" .)