Make good former monarch back revolution (6)
I believe the answer is:
recoup
'make good' is the definition.
(synonyms)
'former monarch back revolution' is the wordplay.
'former monarch' becomes 'ER' (Elizabeth Regina, ie Queen Elizabeth).
'back' says the letters should be written backwards.
'revolution' becomes 'coup' (a coup against the state).
'er' reversed gives 're'.
're'+'coup'='RECOUP'
(Other definitions for recoup that I've seen before include "Regain, make good" , "Get back or recover - say losses" , "Recover, losses perhaps" , "Regain (something lost)" , "recover money" .)