Writer from Zagreb, ironically (4)
I believe the answer is:
biro
'writer' is the definition.
(I've seen this before)
'from zagreb ironically' is the wordplay.
'from' indicates a hidden word.
'BIRO' is hidden within 'zagreb ironically'.
(Other definitions for biro that I've seen before include "writer" , "Type of ballpoint pen" , "Writing implement" , "Laszlo Jozsef -, ballpoint pen inventor" , "Lazlo -, ballpoint pen inventor" .)