Agreements to restrict modified rates all round (8)
I believe the answer is:
treaties
'agreements' is the definition.
(I know this)
'restrict modified rates all round' is the wordplay.
'restrict' becomes 'tie' (tying is a kind of restricting).
'modified' is an anagram indicator.
'all round' is an insertion indicator.
'rates' with letters rearranged gives 'treas'.
'tie' going into 'treas' is 'TREATIES'.
'to' is the link.
(Other definitions for treaties that I've seen before include "Written agreements between states" , "Accords" , "Treatise about pacts" , "Rome and Versailles, for example" , "Treatise on international agreements" .)