Secure weapons after revolution (4)
I believe the answer is:
snug
'secure' is the definition.
(similar in meaning)
'weapons after revolution' is the wordplay.
'weapons' becomes 'guns' (gun is a kind of weapon).
'after revolution' says the letters should be written in reverse (letters revolve back).
'guns' reversed gives 'SNUG'.
(Other definitions for snug that I've seen before include "Well protected or concealed" , "Cosy room" , "Comfy and cosy like bug in rug" , "Cosy retreat" , "Close-fitting and cosy" .)