Zealous fellow in a canal, it turned out (9)
I believe the answer is:
fanatical
'zealous' is the definition.
(thesaurus)
'fellow in a canal it turned out' is the wordplay.
'fellow in' becomes 'fa' (I can't justify this - if you can you should believe this answer much more).
'turned out' indicates an anagram (turn out can mean to organise).
'canal'+'it'='canalit'
'canalit' is an anagram of 'natical'.
'fa'+'natical'='FANATICAL'
Can you help me to learn more?
(Other definitions for fanatical that I've seen before include "Obsessive" , "Excessively zealous" , "Crazily keen" , "Unreasonably zealous" , "Extreme" .)