It is written that in the course of strange rites, you eat (8)
I believe the answer is:
treatise
'it is written that in the course' is the definition.
The definition suggests a singular noun which matches the answer.
'strange rites you eat' is the wordplay.
'strange' indicates anagramming the letters.
'you' becomes 'eat' (I can't explain this - if you can you should believe this answer much more).
'eat' indicates putting letters inside.
'rites' with letters rearranged gives 'trise'.
'trise' placed around 'eat' is 'TREATISE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for treatise that I've seen before include "Systematically-written formal piece" , "Iterates in dissertation" , "Long, detailed essay" , "Thesis" , "Tract, monograph" .)