Attacks disheartened rebels accepting help (5)
I believe the answer is:
raids
'attacks' is the definition.
(I know this)
'disheartened rebels accepting help' is the wordplay.
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'accepting' means one lot of letters goes inside another (inserted letters are accepted).
'help' becomes 'aid' (synonyms).
'rebels' with its middle taken out is 'rs'.
'rs' enclosing 'aid' is 'RAIDS'.
(Other definitions for raids that I've seen before include "Military incursions, forays" , "Sudden attacks" , "Military attacks" , "Surprise attacks" , "Invasions" .)