"Right”, as a blow (4)
I believe the answer is:
slap
This clue is a double definition.
'right' is the first definition.
(I've seen this before)
'a blow' is the second definition.
(slap is a kind of blow)
'as' is the link.
(Other definitions for slap that I've seen before include "Hit with a flat hand" , "Right" , "Blow, maybe in the face" , "Strike with the palm" , "Cuff" .)