Installed as president of Russia (5)
I believe the answer is:
putin
'president of russia' is the definition.
'putin' can be an answer for 'president' (Russian president Vladimir Putin). I am not certain of the 'of russia' bit.
'installed as' is the wordplay.
'installed' becomes 'put' (I can't justify this - if you can you should believe this answer much more).
'as' becomes 'in' (I've seen this in other clues).
'put'+'in'='PUTIN'
Can you help me to learn more?
(Other definitions for putin that I've seen before include "Introduce" , "Russian leader" , "powerful leader" , "Russian president" .)