Club official, more confident following adjustment of rate (9)
I believe the answer is:
treasurer
'club official' is the definition.
(I've seen this before)
'more confident following adjustment of rate' is the wordplay.
'more confident' becomes 'surer' ('sure' can be similar in meaning to 'confident').
'following' means one lot of letters go next to another.
'adjustment of' is an anagram indicator (I've seen this in other clues).
'rate' anagrammed gives 'trea'.
'surer' after 'trea' is 'TREASURER'.
(Other definitions for treasurer that I've seen before include "Financial controller" , "Fund manager" , "he's got the money" , "Club official" , "Council official" .)