More safe after revolution that's frightening (8)
I believe the answer is:
fearsome
'frightening' is the definition.
(I know that frightening can be written as fearsome)
'more safe after revolution' is the wordplay.
'after revolution' indicates anagramming the letters.
'more'+'safe'='moresafe'
'moresafe' is an anagram of 'FEARSOME'.
'that's' is the link.
(Other definitions for fearsome that I've seen before include "Dreadful" , "Daunting" , "Formidable" , "Frightful" , "Frightening, terrible" .)