Wretched end over European Union's accepting nothing (7)
I believe the answer is:
Here is my best explanation:
'wretched' is the definition.
('piteous' can be a synonym of 'wretched')
'end over european union's accepting nothing' is the subsidiary indication.
'end' becomes 'pits' (I am not sure about this - if you are sure you should believe this answer much more).
'over' means one lot of letters goes inside another.
'european union' becomes 'eu'.
'accepting' is an insertion indicator.
'nothing' becomes 'o' (looks like zero - 0).
'eu' going around 'o' is 'eou'.
'pits' going around 'eou' is 'piteous'.
(Other definitions for piteous that I've seen before include "Arousing sorrow and compassion", "Deserving sympathy", "Heart-rending", "Woeful" and "Deserving compassion".)