Got back trouble carrying a box to Baltic state (6)
I believe the answer is:
latvia
'baltic state' is the definition.
(Latvia is an example)
'got back trouble carrying a box' is the wordplay.
'got back' shows that the letters should be reversed in order.
'trouble' becomes 'ail' (synonyms).
'carrying' means one lot of letters goes inside another.
'box' becomes 'tv'.
'ail' backwards is 'lia'.
'a'+'tv'='atv'
'lia' going around 'atv' is 'LATVIA'.
'to' is the link.
(Other definitions for latvia that I've seen before include "Northeast European country" , "Country in northern Europe" , "Baltic state, capital Riga." , "Riga's country" , "Baltic republic" .)