Assumes Republican power divides America repeatedly (6)
I believe the answer is:
usurps
'assumes' is the definition.
('usurp' can be a synonym of 'assume')
'republican power divides america repeatedly' is the wordplay.
'republican' becomes 'r' (abbreviation).
'power' becomes 'p' (symbol in physics).
'divides' means one lot of letters goes inside another.
'america' becomes 'us' (United States).
'repeatedly' indicates the doubling of some letters.
'r'+'p'='rp'
'us' duplicated is 'usus'.
'rp' placed into 'usus' is 'USURPS'.
(Other definitions for usurps that I've seen before include "takes place" , "Takes power or position wrongfully" , "Takes a position of power illegally" , "Arrogates" , "Encroaches upon" .)