A noted passion for old Ireland (4)
I believe the answer is:
eire
'old ireland' is the definition.
'eire' can be an answer for 'ireland' ('Eire' can be a synonym of 'ireland'). I'm not certain of the 'old' bit.
'a noted passion' is the wordplay.
'a noted' becomes 'e' (I can't explain this - if you can you should believe this answer much more).
'passion' becomes 'ire' (I've seen this before).
'e'+'ire'='EIRE'
'for' is the link.
Can you help me to learn more?
(Other definitions for eire that I've seen before include "Southern Ireland" , "Northwest European country" , "Republic across the water" , "Irish name for Ireland" , "Look for (something to happen)" .)