New rate more certain for finance officer (9)
I believe the answer is:
treasurer
'finance officer' is the definition.
(I've seen this before)
'new rate more certain' is the wordplay.
'new' is an anagram indicator.
'more certain' becomes 'surer' ('sure' can be similar in meaning to 'certain').
'rate' with letters rearranged gives 'trea'.
'trea'+'surer'='TREASURER'
'for' is the link.
(Other definitions for treasurer that I've seen before include "Fiscal officer" , "Bursar" , "Financial controller" , "Association member guarding the cash" , "Fund manager" .)