Old boxer appearing in tabloid regularly (3)
I believe the answer is:
ali
'old boxer' is the definition.
(Muhammad Ali)
'tabloid regularly' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'tabloid' are 'ALI'.
'appearing in' acts as a link.
(Other definitions for ali that I've seen before include "Egyptian name" , "girl shortly" , "Muhammad or Baba?" , "Person" , "Muhammad - - , legendary boxer" .)