Plead with English knight to get something nice (7)
I believe the answer is:
entreat
'plead with' is the definition.
(I've seen this in another clue)
'english knight to get something nice' is the wordplay.
'english' becomes 'E' (abbreviation as in OED).
'knight' becomes 'N' (chess abbreviation).
'to get' is a charade indicator (letters next to each other).
'something nice' becomes 'treat' (I can't justify this - if you can you should give a lot more credence to this answer).
'e'+'n'+'treat'='ENTREAT'
Can you help me to learn more?
(Other definitions for entreat that I've seen before include "Request earnestly" , "Beg earnestly or emotionally" , "Sue" , "Beg earnestly, implore" , "go begging?" .)