European country's sea unfortunately full of trash (6)
I believe the answer is:
espana
'european country's' is the definition.
(Espana is an example)
'sea unfortunately full of trash' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'full of' means one lot of letters goes inside another.
'trash' becomes 'pan' (synonyms).
'sea' with letters rearranged gives 'esa'.
'esa' going around 'pan' is 'ESPANA'.
(Other definitions for espana that I've seen before include "Spain for Spaniards" , "Rhapsody by Chabrier" , "Spain in Spanish" .)