What is red, swirling? Not usually this kitchen sight (9)
I believe the answer is:
dishwater
'not usually this kitchen sight' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'what is red swirling?' is the wordplay.
'swirling?' indicates anagramming the letters.
'what'+'is'+'red'='whatisred'
'whatisred' anagrammed gives 'DISHWATER'.
Can you help me to learn more?
(Other definitions for dishwater that I've seen before include "Sink liquid" , "Ultimately it could go down the sink" , "Weak or soiled liquid" , "Dirty washing-up liquid?" .)