Tsar has four before article (4)
I believe the answer is:
ivan
'tsar' is the definition.
(name of several Russian tsars)
'four before article' is the wordplay.
'four' becomes 'IV' (Roman numerals).
'before' is a charade indicator (letters next to each other).
'article' becomes 'an' (indefinite article).
'iv'+'an'='IVAN'
'has' is the link.
(Other definitions for ivan that I've seen before include "Name of six Russian tzars" , "in Russian history" , "Russian tsar called 'the Terrible'" , "his progress in history was terrible!" , "'Terrible' emperor of Russia" .)