Tell Russian leader to cheer up (6)
I believe the answer is:
relate
'tell' is the definition.
(as in to tell or relate a story)
'russian leader to cheer up' is the wordplay.
'leader' suggests taking the first letters.
'to cheer up' becomes 'elate' (I've seen this in another clue).
The first letter of 'russian' is 'r'.
'r'+'elate'='RELATE'
(Other definitions for relate that I've seen before include "Give account of (story)" , "Recite - marriage guidance organisation" , "Give a report or show a connection" , "Make a logical or causal connection" , "Narrate in Tralee" .)