Make changes, having turned up link across Germany (4)
I believe the answer is:
edit
'make changes' is the definition.
(I've seen this in another clue)
'turned up link across germany' is the wordplay.
'turned up' says the letters should be written backwards.
'link' becomes 'tie' (synonyms).
'across' means one lot of letters goes inside another.
'germany' becomes 'd' (vehicle registration code for Deutschland).
'tie' going around 'd' is 'tide'.
'tide' backwards is 'EDIT'.
'having' acts as a link.
(Other definitions for edit that I've seen before include "Alter text" , "Prepare text for publication" , "Blue-pencil" , "Revise text" , "What our boss does" .)