Arabian fellow visiting Sofia regularly (5)
I believe the answer is:
omani
'arabian' is the definition.
(Omani is an example)
'fellow visiting sofia regularly' is the wordplay.
'fellow' becomes 'man' (I've seen this before).
'visiting' is an insertion indicator.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'sofia' are 'oi'.
'man' put into 'oi' is 'OMANI'.
(Other definitions for omani that I've seen before include "Middle East national" , "One from Muscat" , "Speaker of Arabic" , "coming from the Middle East" , "Asian" .)