Reel from a wallop (3,5)
I believe the answer is:
see stars
'reel from a wallop' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for see stars that I've seen before include "as one may on beautiful night" , "affected by flashing lights" , "You may after whack on the head" , "Be stunned" , "Look dazed" .)