Rulers showing false remorse about start of purge (8)
I believe the answer is:
emperors
'rulers' is the definition.
(emperor is a kind of ruler)
'false remorse about start of purge' is the wordplay.
'false' indicates anagramming the letters.
'about' is an insertion indicator.
'start of' indicates taking the first letters.
The initial letter of 'purge' is 'p'.
'remorse' with letters rearranged gives 'emerors'.
'emerors' enclosing 'p' is 'EMPERORS'.
'showing' acts as a link.
(Other definitions for emperors that I've seen before include "Rulers of great territories" , "Tsars" .)