Help with attack annihilating resistance (3)
I believe the answer is:
aid
'help' is the definition.
(synonyms)
'attack annihilating resistance' is the wordplay.
'attack' becomes 'raid' (raiding is a kind of attacking).
'annihilating' indicates named letters should be taken away.
'resistance' becomes 'r' (abbreviation in physics and electronics).
'raid' with 'r' taken out is 'AID'.
'with' is the link.
(Other definitions for aid that I've seen before include "grant" , "encouragement" , "Care, assistance" , "welfare" , "Relief" .)