Club official more confident following change of rate (9)
I believe the answer is:
treasurer
'club official' is the definition.
(I've seen this before)
'more confident following change of rate' is the wordplay.
'more confident' becomes 'surer' ('sure' can be similar in meaning to 'confident').
'following' says to put letters next to each other.
'change of' indicates an anagram (the letter order is changed).
'rate' is an anagram of 'trea'.
'surer' put after 'trea' is 'TREASURER'.
(Other definitions for treasurer that I've seen before include "Fund manager" , "Financial administrator" , "position in society?" , "Society official" , "Finance expert" .)