Let's arrange to display Russian leader (4)
I believe the answer is:
tsar
'russian leader' is the definition.
(I've seen this before)
'let's arrange to display' is the wordplay.
'to display' indicates a hidden word (I've seen 'displaying' mean this).
'TSAR' is hidden in the letters of 'lets arrange'.
(Other definitions for tsar that I've seen before include "Nicholas II, say" , "Monarch of old Russia" , "Old leader" , "Old Russian ruler" , "Potentate" .)