Fool troubled saint, not ultimately one to help (9)
I believe the answer is:
assistant
'one to help' is the definition.
('assistant' can be a synonym of 'help')
'fool troubled saint not ultimately' is the wordplay.
'fool' becomes 'ass' (ass is a kind of fool**).
'troubled' indicates an anagram.
'ultimately' says to take the final letters.
The final letter of 'not' is 't'.
'saint' anagrammed gives 'istan'.
'ass'+'istan'+'t'='ASSISTANT'
(Other definitions for assistant that I've seen before include "Deputy, subordinate" , "help required?" , "Aide, helper" , "one helps out" , "Attendant, helper" .)