Particularly sound judgment, English admitted, not essential (10)
I believe the answer is:
extraneous
'not essential' is the definition.
(I've seen this in another clue)
'particularly sound judgment english admitted' is the wordplay.
'particularly' becomes 'extra' (synonyms).
'sound judgment' becomes 'nous' (nous is a kind of judgment. I am not sure about the 'sound' bit.).
'english' becomes 'e' (abbreviation).
'admitted' is an insertion indicator.
'nous' going around 'e' is 'neous'.
'extra'+'neous'='EXTRANEOUS'
Can you help me to learn more?
(Other definitions for extraneous that I've seen before include "Of external origin" , "Unrelated to the subject" , "immaterial" , "not essential" , "Unrelated, irrelevant" .)