Poland agreed to import new wine (5)
I believe the answer is:
plonk
'wine' is the definition.
(I know that plonk is a type of wine)
'poland agreed to import new' is the wordplay.
'poland' becomes 'PL' (e.g. on number plates).
'agreed' becomes 'ok' (eg when responding to an offer).
'to import' indicates putting letters inside.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'ok' going around 'n' is 'onk'.
'pl'+'onk'='PLONK'
(Other definitions for plonk that I've seen before include "Cheap red or white" , "Put down - cheap wine" , "Wine - put down with a thud" , "cheap drink" , "Put down noisily" .)