Two-sided legislation about a rate change (9)
I believe the answer is:
bilateral
'two-sided' is the definition.
(synonyms)
'legislation about a rate change' is the wordplay.
'legislation' becomes 'bill' (eg a bill in parliament).
'about' means one lot of letters goes inside another.
'change' indicates an anagram.
'a'+'rate'='arate'
'arate' anagrammed gives 'atera'.
'bill' going around 'atera' is 'BILATERAL'.
(Other definitions for bilateral that I've seen before include "Two-sided" , "involving two sides" , "Involving two parties" , "Undertaken by two parties" , "involving more than one party?" .)