Salvationists beat the Devil (5)
I believe the answer is:
satan
'the devil' is the definition.
('Satan' can be a synonym of 'devil')
'salvationists beat' is the wordplay.
'salvationists' becomes 'sa' (I've seen this in other clues).
'beat' becomes 'tan' (I've seen this before).
'sa'+'tan'='SATAN'
(Other definitions for satan that I've seen before include "The devil, Beelzebub" , "Fallen archangel" , "Fiend" , "Prince of Darkness" , "Apollyon" .)