Infamous old port protected by other people? (9)
I believe the answer is:
notorious
'infamous' is the definition.
('notorious' can be a synonym of 'infamous')
'old port protected by other people?' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'port' becomes 'rio' (I've seen this before).
'protected by' indicates putting letters inside.
'other people?' becomes 'notus' (I am not sure about this - if you are sure you should believe this answer much more).
'o'+'rio'='orio'
'orio' going into 'notus' is 'NOTORIOUS'.
(Other definitions for notorious that I've seen before include "Hitchcock film" , "Famous for something bad" , "having a terrible reputation?" , "worthy of shame?" , "Scandalous" .)