Heading north, attacked to achieve rescue (7)
I believe the answer is:
deliver
'to achieve rescue' is the definition.
'heading north attacked' is the wordplay.
'heading north' shows that the letters should be reversed in order.
'attacked' becomes 'reviled'.
'reviled' written backwards gives 'DELIVER'.
(Other definitions for deliver that I've seen before include "Bring into the world - set free" , "Handover" , "what the errand boy does" , "Transfer and hand over" , "launch" .)