Man a terrible tsar? Not very (3)
I believe the answer is:
ian
'man' is the definition.
(man's name)
'a terrible tsar? not very' is the wordplay.
'a terrible tsar?' becomes 'ivan' (Ivan the Terrible).
'not' is a deletion indicator.
'very' becomes 'v' (common abbreviation).
'ivan' with 'v' taken away is 'IAN'.
(Other definitions for ian that I've seen before include "The familiar Mr Paisley" , "Botham or Chappell?" , "Male" , "- McEwan, Eng. writer" , "Scotsman?" .)