Republican helps attacks (5)
I believe the answer is:
raids
'attacks' is the definition.
(raid is a kind of attack)
'republican helps' is the wordplay.
'republican' becomes 'r' (abbreviation).
'helps' becomes 'aids' ('aid' can be a synonym of 'help').
'r'+'aids'='RAIDS'
(Other definitions for raids that I've seen before include "Military attacks" , "Invasions" , "Sudden attacks" , "Surprise attacks" , "Military incursions, forays" .)