A good man rises to king and emperor (4)
I believe the answer is:
tsar
'emperor' is the definition.
(I've seen this before)
'a good man rises to king' is the wordplay.
'good man' becomes 'st'.
'rises' shows that the letters should be reversed in order.
'to king' becomes 'r' (r is abbreviation for rex).
'a'+'st'='ast'
'ast' written backwards gives 'tsa'.
'tsa'+'r'='TSAR'
'and' acts as a link.
(Other definitions for tsar that I've seen before include "Person in charge" , "Supremo" , "Rats to the Russian emperor" , "Monarch of old Russia" , "Once-powerful Russian" .)