Starts with the straight approach — right for leader (4)
I believe the answer is:
tsar
'leader' is the definition.
(I've seen this before)
'starts with the straight approach right' is the wordplay.
'starts with' says to take the initial letters.
The initial letters of 'the straight approach right' is 'TSAR'.
'for' is the link.
(Other definitions for tsar that I've seen before include "Powerful man" , "Word derived from Caesar, used by European rulers since 1547" , "A former Russian ruler - rats to him" , "Tyrant" , "Ruler finally executed" .)