Become enraged (6)
'become enraged' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for see red that I've seen before include "blow a gasket" , "Be annoyed" , "Lose temper like angry bull" , "Lose temper like raging bull" , "Burst a blood vessel" .)
(Another definition for seered that I've seen is " Grow furious".)