Repeatedly thanks Russia's leader in Turkic language (5)
I believe the answer is:
tatar
'turkic language' is the definition.
(Tatar is an example)
'repeatedly thanks russia's leader' is the wordplay.
'repeatedly' shows that letters should be duplicated.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'leader' suggests taking the first letters.
The initial letter of 'russias' is 'r'.
'ta' doubled is 'tata'.
'tata'+'r'='TATAR'
'in' is the link.
(Other definitions for tatar that I've seen before include "Member of a people living in Ukraine and Russia" , "Turkic language" , "Old warrior" , "Mongol warrior" , "Russian" .)