Appeals for readjustment after pa, upset, has left (5)
I believe the answer is:
pleas
'appeals for readjustment' is the definition.
'pleas' can be an answer for 'appeals' (I've seen this in another clue). I am not certain of the 'for readjustment' bit.
'pa upset has left' is the wordplay.
'pa upset' becomes 'peas' (I am not sure about this - if you are sure you should believe this answer much more).
'has' means one lot of letters goes inside another.
'left' becomes 'l' (common abbreviation).
'peas' placed around 'l' is 'PLEAS'.
'after' acts as a link.
Can you help me to learn more?
(Other definitions for pleas that I've seen before include "Urgent entreaties" , "Excuses, pretexts" , "Entreats" .)