The one that didn't get on with you (4)
I believe the answer is:
thee
'you' is the definition.
(historical second person pronoun)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for thee that I've seen before include "Quaker 'you'" , "Archaic form of 'you'" , "Poetically you" , "You in the olden days" , "You (arch.)" .)