Exceptional charm almost taking in agents (7)
I believe the answer is:
special
'exceptional' is the definition.
('special' can be a synonym of 'exceptional')
'charm almost taking in agents' is the wordplay.
'charm' becomes 'spell' (I've seen this before).
'almost' means to remove the last letter (most of the word but not all of it).
'taking' indicates putting letters inside.
'in agents' becomes 'cia' (I am not sure about this - if you are sure you should believe this answer much more).
'spell' with its final letter taken away is 'spel'.
'spel' enclosing 'cia' is 'SPECIAL'.
Can you help me to learn more?
(Other definitions for special that I've seen before include "Quite out of the ordinary" , "Dish not on usual menu" , "Distinct from and usually better" , "Important; particular" , "Out of the ordinary, singular" .)