A citizen of Zagreb? (5)
I believe the answer is:
croat
'a citizen of zagreb?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for croat that I've seen before include "One from Zagreb" , "One of the races of former Yugoslavia" , "eg Native of Zagreb" , "From Zagreb, perhaps" , "Actor (anag.)" .)