Once changed, honour goes to first specialist (9)
I believe the answer is:
economist
'specialist' is the definition.
(I have seen 'Financial specialist' mean 'economist' so perhaps 'specialist' could also mean 'economist')
'once changed honour goes to first' is the wordplay.
'changed' indicates an anagram.
'honour' becomes 'om' (Order of Merit).
'goes to' says to put letters next to each other.
'first' becomes 'ist' (ist resembles 1st).
'once' anagrammed gives 'econ'.
'econ'+'om'+'ist'='ECONOMIST'
(Other definitions for economist that I've seen before include "Friedman, say" , "Financial expert" , "Comes into (anag)" , "He studies money etc" , "John Maynard Keynes for instance" .)