Heard northern European language in the end (6)
I believe the answer is:
finish
'the end' is the definition.
(I've seen this before)
'heard northern european language' is the wordplay.
'heard' indicates a 'sounds like' (homophone) clue.
'northern european language' becomes 'Finnish' (language of Finland).
'finnish' is a homophone of 'FINISH'.
'in' is the link.
(Other definitions for finish that I've seen before include "'End, close (6)'" , "Pefect" , "Bring to an end" , "Terminate, conclude" , "curtains" .)