Old Baltic port initially misrepresented in Japanese art (7)
I believe the answer is:
origami
'japanese art' is the definition.
(I've seen this in another clue)
'old baltic port initially misrepresented in' is the wordplay.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'baltic port' becomes 'riga' (capital of Latvia, a Baltic nation).
'initially' says to take the initial letters.
The first letters of 'misrepresented in' is 'mi'.
'o'+'riga'+'mi'='ORIGAMI'
(Other definitions for origami that I've seen before include "US record label" , "Japanese craft of paper-tearing" , "folding stuff?" , "Creation of objects from paper" , "Paper-folding skill" .)