Red? Emphatically! (5)
I believe the answer is:
ruddy
'red?' is the definition.
(I know that blood-red can be written as ruddy)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ruddy that I've seen before include "Damn" , "Florid (of face)" , "Glowing pink" , "Bright" , "blasted" .)