Arrive from above and vanquish? (8)
I believe the answer is:
overcome
'vanquish?' is the definition.
('overcome' can be a synonym of 'vanquish')
'arrive from above' is the wordplay.
'arrive' becomes 'come' (coming is a kind of arriving).
'from' becomes 'over' (I can't explain this - if you can you should give a lot more credence to this answer).
'above' means one lot of letters go next to another (in a down clue, some letters go above others).
'come' after 'over' is 'OVERCOME'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for overcome that I've seen before include "hammer" , "Succeed in dealing with difficulties" , "Get the better of" , "Come over in order to conquer" , "Emotional" .)