Meat prices go up before the end of June - some achievement! (11)
I believe the answer is:
masterpiece
'some achievement' is the definition.
(masterpiece is a kind of achievement)
'meat prices go up before' is the wordplay.
'meat' becomes 'piece' (piece is a kind of meat).
'prices go up' becomes 'master' (I can't justify this - if you can you should believe this answer much more).
'before' means one lot of letters go next to another.
'piece' put after 'master' is 'MASTERPIECE'.
'the end of june' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for masterpiece that I've seen before include "outstanding achievement" , "Superb work of art" , "Outstanding artwork" , "major artwork" , "Work of extreme skill" .)