Slaughter of the alliterative? (5,4)

I believe the answer is:
blood bath
'slaughter' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I don't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for blood bath that I've seen before include "in which many die" , "A sanguinary massacre - cleansing?" , "A gory massacre - might be cleansing?" .)
