East European given piece of butter to turn into culinary paste (8)
I believe the answer is:
tapenade
'culinary paste' is the definition.
(type of paste used in French cuisine)
'east european given piece of butter to turn' is the wordplay.
'east' becomes 'e' (synonyms).
'european given piece of' becomes 'dane' (I can't justify this - if you can you should give a lot more credence to this answer).
'butter' becomes 'pat' (a pat can mean a lump of butter).
'to turn' shows that the letters should be reversed in order.
'e'+'dane'+'pat'='edanepat'
'edanepat' in reverse letter order is 'TAPENADE'.
'into' is the link.
(Other definitions for tapenade that I've seen before include "Paste of olives with capers and anchovies" , "Provencal savoury dip of olives, capers, anchovies" .)