Russian ruler 'beats a retreat' ... bottles it (4)
I believe the answer is:
tsar
'russian ruler' is the definition.
(I've seen this in another clue)
'beats a retreat bottles it' is the wordplay.
'beats a retreat' becomes 'tr' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'bottles' is an insertion indicator (bottle can mean to contain).
'it' becomes 'sa' (old-fashioned abbreviation for sex appeal).
'tr' placed around 'sa' is 'TSAR'.
Can you help me to learn more?
(Other definitions for tsar that I've seen before include "Word derived from Caesar, used by European rulers since 1547" , "Old Russian 22" , "Nicholas II was the last" , "Old leader" , "Peter the Great, for example" .)