Surviving a terrible evil (5)
I believe the answer is:
alive
'surviving' is the definition.
(I've seen this before)
'a terrible evil' is the wordplay.
'terrible' indicates anagramming the letters.
'evil' anagrammed gives 'live'.
'a'+'live'='ALIVE'
(Other definitions for alive that I've seen before include "Breathing, existing" , "Spirited" , "Still with us" , "In existence" , "''Crying cockles and mussels, ..., ..., oh'' (Molly Malone)" .)