Earliest proper toilet English rebuffed (8)
I believe the answer is:
primeval
'earliest proper toilet english rebuffed' is the definition.
I can't tell whether this definition defines the answer.
'proper toilet english rebuffed' is the wordplay.
'proper' becomes 'prim' ('prim' can be similar in meaning to 'proper').
'toilet' becomes 'lav' ('lav' can be a synonym of 'toilet').
'english' becomes 'e' (abbreviation).
'rebuffed' says the letters should be written backwards.
'lav'+'e'='lave'
'lave' in reverse letter order is 'eval'.
'prim'+'eval'='PRIMEVAL'
Can you help me to learn more?
(Other definitions for primeval that I've seen before include "From the earliest times" , "Ancient" , "Very old" , "Belonging to the Earth's beginnings" , "having come first in history" .)