Foreign film's a new one on me (5)
I believe the answer is:
anime
'foreign film's' is the definition.
(type of Japanese animation)
'a new one on me' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'one' becomes 'i' (Roman numeral).
'on' means one lot of letters go next to another.
'a'+'n'+'i'+'me'='ANIME'
(Other definitions for anime that I've seen before include "Drawing style" , "Japanese cartoon style" , "style of Japanese film" , "Japanese cartoon film genre" .)