Holy man turns to a king and emperor (4)
I believe the answer is:
tsar
'emperor' is the definition.
(I've seen this before)
'holy man turns to a king' is the wordplay.
'holy man' becomes 'st' (abbreviation for saint).
'turns' says the letters should be written backwards.
'to' is a charade indicator (letters next to each other).
'king' becomes 'R' (abbreviation of Latin rex).
'st' back-to-front is 'ts'.
'ts'+'a'+'r'='TSAR'
'and' acts as a link.
(Other definitions for tsar that I've seen before include "Person in charge" , "Alexander and Nicholas held this title in Russia" , "Rats to the Russian emperor" , "One associated with 26 [KREMLIN]" , "specific authority" .)