Attacking band with inside help (7)
I believe the answer is:
raiding
'attacking' is the definition.
(raiding is a kind of attacking)
'band with inside help' is the wordplay.
'band' becomes 'ring' (a ring is a band of metal).
'with' is an insertion indicator.
'inside help' becomes 'aid' (synonyms. I am not sure about the 'inside' bit.).
'ring' going around 'aid' is 'RAIDING'.
Can you help me to learn more?
(Other definitions for raiding that I've seen before include "Plundering" , "Attacking" , "Making inroads" .)