Fixed and converted into a material thing around court (9)
I believe the answer is:
rectified
'fixed and converted' is the definition.
I can't judge whether this defines the answer.
'into a material thing around court' is the wordplay.
'into' means one lot of letters goes inside another.
'a material thing' becomes 'deifier' (I am not sure about this - if you are sure you should believe this answer much more).
'around' says the letters should be written backwards.
'court' becomes 'ct' (abbreviation used in road names).
'deifier' back-to-front is 'reified'.
'reified' enclosing 'ct' is 'RECTIFIED'.
Can you help me to learn more?
(Other definitions for rectified that I've seen before include "Put right" , "repaired" .)