Haggle for a year to get the agreement (6)
I believe the answer is:
treaty
'agreement' is the definition.
(treaty is a kind of agreement)
'haggle for a year to get the' is the wordplay.
'haggle for' becomes 'tre' (I am not sure about this - if you are sure you should believe this answer much more).
'year' becomes 'y'.
'to get' means one lot of letters go next to another.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'y' put after 't' is 'ty'.
'tre'+'a'+'ty'='TREATY'
Can you help me to learn more?
(Other definitions for treaty that I've seen before include "Formal agreement between states" , "Political or private agreement" , "Formal pact" , "A pact between countries" , "Covenant" .)