Bounder crazy about port (9)
I believe the answer is:
rotterdam
'port' is the definition.
(I've seen this before)
'bounder crazy about' is the wordplay.
'bounder' becomes 'rotter' (I've seen this before).
'crazy' becomes 'mad' ('mad' can be a synonym of 'crazy').
'about' says the letters should be written in reverse.
'mad' written backwards gives 'dam'.
'rotter'+'dam'='ROTTERDAM'
(Other definitions for rotterdam that I've seen before include "Netherlands port" , "European port" , "Dutch city and port" , "European city" , "city abroad" .)